Mercurial > minori
view dep/fmt/doc/html/api.html @ 343:1faa72660932
*: transfer back to cmake from autotools
autotools just made lots of things more complicated than
they should have and many things broke (i.e. translations)
| author | Paper <paper@paper.us.eu.org> |
|---|---|
| date | Thu, 20 Jun 2024 05:56:06 -0400 |
| parents | |
| children |
line wrap: on
line source
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" /> <title>API Reference — fmt 10.2.1 documentation</title> <link rel="stylesheet" href="_static/basic.css" type="text/css" /> <link rel="stylesheet" href="_static/pygments.css" type="text/css" /> <link rel="stylesheet" href="_static/breathe.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: './', VERSION: '10.2.1', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', LINK_SUFFIX: '.html', SOURCELINK_SUFFIX: '.txt', HAS_SOURCE: true, SOURCELINK_SUFFIX: '.txt' }; </script> <script src="_static/jquery.js"></script> <script src="_static/underscore.js"></script> <script src="_static/doctools.js"></script> <script src="_static/language_data.js"></script> <link rel="index" title="Index" href="genindex.html" /> <link rel="search" title="Search" href="search.html" /> <meta name="description" content="Small, safe and fast formatting library"> <meta name="keywords" content="C++, formatting, printf, string, library"> <meta name="author" content="Victor Zverovich"> <link rel="stylesheet" href="_static/fmt.css"> <script async src="https://www.googletagmanager.com/gtag/js?id=UA-20116650-4"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'UA-20116650-4'); </script> </head> <body role="document"> <nav class="navbar navbar-inverse"> <div class="tb-container"> <div class="row"> <div class="navbar-content"> <div class="navbar-header"> <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target=".navbar-collapse"> <span class="sr-only">Toggle navigation</span> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a class="navbar-brand" href="index.html">{fmt}</a> </div> <div class="collapse navbar-collapse"> <ul class="nav navbar-nav"> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-expanded="false">10.2.1 <span class="caret"></span></a> <ul class="dropdown-menu" role="menu"> <li><a href="https://fmt.dev/10.2.1">10.2.1</a></li> <li><a href="https://fmt.dev/10.2.0">10.2.0</a></li> <li><a href="https://fmt.dev/10.1.1">10.1.1</a></li> </ul> </li> <li><a href="contents.html">Contents</a></li> <li><a href="usage.html">Usage</a></li> <li class="active"><a href="api.html">API <span class="sr-only">(current)</span></a></li> <li><a href="syntax.html">Syntax</a></li> </ul> <form class="navbar-form navbar-right" role="search" action="search.html" method="get"> <div class="form-group"> <input type="text" name="q" class="form-control" placeholder="Search" > </div> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div> </div> </div> </nav> <div class="tb-container"> <div class="row"> <div class="content"> <section id="api-reference"> <span id="string-formatting-api"></span><h1>API Reference<a class="headerlink" href="#api-reference" title="Permalink to this headline">¶</a></h1> <p>The {fmt} library API consists of the following parts:</p> <ul class="simple"> <li><p><a class="reference internal" href="#core-api"><span class="std std-ref">fmt/core.h</span></a>: the core API providing main formatting functions for <code class="docutils literal notranslate"><span class="pre">char</span></code>/UTF-8 with C++20 compile-time checks and minimal dependencies</p></li> <li><p><a class="reference internal" href="#format-api"><span class="std std-ref">fmt/format.h</span></a>: the full format API providing additional formatting functions and locale support</p></li> <li><p><a class="reference internal" href="#ranges-api"><span class="std std-ref">fmt/ranges.h</span></a>: formatting of ranges and tuples</p></li> <li><p><a class="reference internal" href="#chrono-api"><span class="std std-ref">fmt/chrono.h</span></a>: date and time formatting</p></li> <li><p><a class="reference internal" href="#std-api"><span class="std std-ref">fmt/std.h</span></a>: formatters for standard library types</p></li> <li><p><a class="reference internal" href="#compile-api"><span class="std std-ref">fmt/compile.h</span></a>: format string compilation</p></li> <li><p><a class="reference internal" href="#color-api"><span class="std std-ref">fmt/color.h</span></a>: terminal color and text style</p></li> <li><p><a class="reference internal" href="#os-api"><span class="std std-ref">fmt/os.h</span></a>: system APIs</p></li> <li><p><a class="reference internal" href="#ostream-api"><span class="std std-ref">fmt/ostream.h</span></a>: <code class="docutils literal notranslate"><span class="pre">std::ostream</span></code> support</p></li> <li><p><a class="reference internal" href="#args-api"><span class="std std-ref">fmt/args.h</span></a>: dynamic argument lists</p></li> <li><p><a class="reference internal" href="#printf-api"><span class="std std-ref">fmt/printf.h</span></a>: <code class="docutils literal notranslate"><span class="pre">printf</span></code> formatting</p></li> <li><p><a class="reference internal" href="#xchar-api"><span class="std std-ref">fmt/xchar.h</span></a>: optional <code class="docutils literal notranslate"><span class="pre">wchar_t</span></code> support</p></li> </ul> <p>All functions and types provided by the library reside in namespace <code class="docutils literal notranslate"><span class="pre">fmt</span></code> and macros have prefix <code class="docutils literal notranslate"><span class="pre">FMT_</span></code>.</p> <section id="core-api"> <span id="id1"></span><h2>Core API<a class="headerlink" href="#core-api" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/core.h</span></code> defines the core API which provides main formatting functions for <code class="docutils literal notranslate"><span class="pre">char</span></code>/UTF-8 with C++20 compile-time checks. It has minimal include dependencies for better compile times. This header is only beneficial when using {fmt} as a library (the default) and not in the header-only mode. It also provides <code class="docutils literal notranslate"><span class="pre">formatter</span></code> specializations for built-in and string types.</p> <p>The following functions use <a class="reference internal" href="syntax.html#syntax"><span class="std std-ref">format string syntax</span></a> similar to that of Python’s <a class="reference external" href="https://docs.python.org/3/library/stdtypes.html#str.format">str.format</a>. They take <em>fmt</em> and <em>args</em> as arguments.</p> <p><em>fmt</em> is a format string that contains literal text and replacement fields surrounded by braces <code class="docutils literal notranslate"><span class="pre">{}</span></code>. The fields are replaced with formatted arguments in the resulting string. <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_string</span></code></a> is a format string which can be implicitly constructed from a string literal or a <code class="docutils literal notranslate"><span class="pre">constexpr</span></code> string and is checked at compile time in C++20. To pass a runtime format string wrap it in <a class="reference internal" href="#_CPPv4N3fmt7runtimeE11string_view" title="fmt::runtime"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">fmt::runtime()</span></code></a>.</p> <p><em>args</em> is an argument list representing objects to be formatted.</p> <p>I/O errors are reported as <a class="reference external" href="https://en.cppreference.com/w/cpp/error/system_error">std::system_error</a> exceptions unless specified otherwise.</p> <span class="target" id="format"></span><dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt6formatENSt6stringE13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt6formatE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt6formatE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1a6dd296c9100bdd4939538068b77bdfe1"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt6formatENSt6stringE13format_stringIDp1TEDpRR1T" title="fmt::format::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt6formatENSt6stringE13format_stringIDp1TEDpRR1T" title="fmt::format::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt6formatENSt6stringE13format_stringIDp1TEDpRR1T" title="fmt::format::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> std::string<a class="headerlink" href="#_CPPv4IDpEN3fmt6formatENSt6stringE13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code> and returns the result as a string.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/core.h></span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">message</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"The answer is {}."</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt7vformatE11string_view11format_args"> <span id="_CPPv3N3fmt7vformatE11string_view11format_args"></span><span id="_CPPv2N3fmt7vformatE11string_view11format_args"></span><span id="fmt::vformat__string_view.format_args"></span><span class="target" id="core_8h_1a3688aa4186696a1231623bde7775a953"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4N3fmt7vformatE11string_view11format_args" title="fmt::vformat::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">vformat</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>fmt</em>, <a class="reference internal" href="#_CPPv4N3fmt11format_argsE" title="fmt::format_args">format_args</a> <em>args</em><span class="sig-paren">)</span> -> std::string<a class="headerlink" href="#_CPPv4N3fmt7vformatE11string_view11format_args" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T"> <span id="_CPPv3I0DpEN3fmt9format_toE8OutputIt13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2I0DpEN3fmt9format_toE8OutputIt13format_stringIDp1TEDpRR1T"></span>template<typename <code class="sig-name descname">OutputIt</code>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1a0ca5ab5f03a0c86633550f1dd5744577"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_to</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to::OutputIt">OutputIt</a> <em>out</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> <a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to::OutputIt">OutputIt</a><a class="headerlink" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code>, writes the result to the output iterator <code class="docutils literal notranslate"><span class="pre">out</span></code> and returns the iterator past the end of the output range. <a class="reference internal" href="#_CPPv4I0DpEN3fmt9format_toE8OutputIt8OutputIt13format_stringIDp1TEDpRR1T" title="fmt::format_to"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_to()</span></code></a> does not append a terminating null character.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span><span class="w"> </span><span class="n">out</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="kt">char</span><span class="o">></span><span class="p">();</span> <span class="n">fmt</span><span class="o">::</span><span class="n">format_to</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">back_inserter</span><span class="p">(</span><span class="n">out</span><span class="p">),</span><span class="w"> </span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T"> <span id="_CPPv3I0DpEN3fmt11format_to_nE8OutputIt6size_t13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2I0DpEN3fmt11format_to_nE8OutputIt6size_t13format_stringIDp1TEDpRR1T"></span>template<typename <code class="sig-name descname">OutputIt</code>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1af2a17cefc40c6d780369144c5de1e2af"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_to_n</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n::OutputIt">OutputIt</a> <em>out</em>, size_t <em>n</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> <a class="reference internal" href="#_CPPv4I0EN3fmt18format_to_n_resultE" title="fmt::format_to_n_result">format_to_n_result</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n::OutputIt">OutputIt</a>><a class="headerlink" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code>, writes up to <code class="docutils literal notranslate"><span class="pre">n</span></code> characters of the result to the output iterator <code class="docutils literal notranslate"><span class="pre">out</span></code> and returns the total (not truncated) output size and the iterator past the end of the output range. <a class="reference internal" href="#_CPPv4I0DpEN3fmt11format_to_nE18format_to_n_resultI8OutputItE8OutputIt6size_t13format_stringIDp1TEDpRR1T" title="fmt::format_to_n"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_to_n()</span></code></a> does not append a terminating null character.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt14formatted_sizeE6size_t13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt14formatted_sizeE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt14formatted_sizeE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1a009f905ac9329b59e440fd4c2460d44c"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt14formatted_sizeE6size_t13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">formatted_size</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt14formatted_sizeE6size_t13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt14formatted_sizeE6size_t13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> size_t<a class="headerlink" href="#_CPPv4IDpEN3fmt14formatted_sizeE6size_t13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns the number of chars in the output of <code class="docutils literal notranslate"><span class="pre">format(fmt,</span> <span class="pre">args...)</span></code>. </p> </dd></dl> <dl class="cpp struct"> <dt id="_CPPv4I0EN3fmt18format_to_n_resultE"> <span id="_CPPv3I0EN3fmt18format_to_n_resultE"></span><span id="_CPPv2I0EN3fmt18format_to_n_resultE"></span>template<typename <code class="sig-name descname">OutputIt</code>><br /><span class="target" id="structfmt_1_1format__to__n__result"></span><em class="property">struct </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_to_n_result</code><a class="headerlink" href="#_CPPv4I0EN3fmt18format_to_n_resultE" title="Permalink to this definition">¶</a><br /></dt> <dd><div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Members</p> <dl class="cpp var"> <dt id="_CPPv4N3fmt18format_to_n_result3outE"> <span id="_CPPv3N3fmt18format_to_n_result3outE"></span><span id="_CPPv2N3fmt18format_to_n_result3outE"></span><span id="fmt::format_to_n_result::out__OutputIt"></span><span class="target" id="structfmt_1_1format__to__n__result_1a71d11006ad16fba226096f94c21b037e"></span><a class="reference internal" href="#_CPPv4I0EN3fmt18format_to_n_resultE" title="fmt::format_to_n_result::OutputIt">OutputIt</a> <code class="sig-name descname">out</code><a class="headerlink" href="#_CPPv4N3fmt18format_to_n_result3outE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Iterator past the end of the output range. </p> </dd></dl> <dl class="cpp var"> <dt id="_CPPv4N3fmt18format_to_n_result4sizeE"> <span id="_CPPv3N3fmt18format_to_n_result4sizeE"></span><span id="_CPPv2N3fmt18format_to_n_result4sizeE"></span><span id="fmt::format_to_n_result::size__s"></span><span class="target" id="structfmt_1_1format__to__n__result_1a2dd58f1d85be6662df6fdfd943aecc88"></span>size_t <code class="sig-name descname">size</code><a class="headerlink" href="#_CPPv4N3fmt18format_to_n_result4sizeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Total (not truncated) output size. </p> </dd></dl> </div> </dd></dl> <span class="target" id="print"></span><dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt5printEv13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt5printE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt5printE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1ac0252a192c582b07d6398e7df4f84ec7"></span>void <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt5printEv13format_stringIDp1TEDpRR1T" title="fmt::print::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">print</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt5printEv13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt5printEv13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>&&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt5printEv13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code> and writes the output to <code class="docutils literal notranslate"><span class="pre">stdout</span></code>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Elapsed time: {0:.2f} seconds"</span><span class="p">,</span><span class="w"> </span><span class="mf">1.23</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt6vprintE11string_view11format_args"> <span id="_CPPv3N3fmt6vprintE11string_view11format_args"></span><span id="_CPPv2N3fmt6vprintE11string_view11format_args"></span><span id="fmt::vprint__string_view.format_args"></span><span class="target" id="core_8h_1a09c43e4ca3fd68c12d08b3de59229400"></span>void <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4N3fmt6vprintE11string_view11format_args" title="fmt::vprint::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">vprint</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>fmt</em>, <a class="reference internal" href="#_CPPv4N3fmt11format_argsE" title="fmt::format_args">format_args</a> <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt6vprintE11string_view11format_args" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt5printEvPNSt4FILEE13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt5printEPNSt4FILEE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt5printEPNSt4FILEE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1a92c3da68a9590d3233b95ffa1f91fa7b"></span>void <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvPNSt4FILEE13format_stringIDp1TEDpRR1T" title="fmt::print::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">print</code><span class="sig-paren">(</span>std::FILE *<em>f</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvPNSt4FILEE13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvPNSt4FILEE13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>&&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt5printEvPNSt4FILEE13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code> and writes the output to the file <code class="docutils literal notranslate"><span class="pre">f</span></code>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span><span class="w"> </span><span class="s">"Don't {}!"</span><span class="p">,</span><span class="w"> </span><span class="s">"panic"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt6vprintEPNSt4FILEE11string_view11format_args"> <span id="_CPPv3N3fmt6vprintEPNSt4FILEE11string_view11format_args"></span><span id="_CPPv2N3fmt6vprintEPNSt4FILEE11string_view11format_args"></span><span id="fmt::vprint__std::FILEP.string_view.format_args"></span><span class="target" id="core_8h_1a59d85226f0b53348b3c8b9a1c88a6daa"></span>void <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4N3fmt6vprintEPNSt4FILEE11string_view11format_args" title="fmt::vprint::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">vprint</code><span class="sig-paren">(</span>std::FILE *<em>f</em>, <a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>fmt</em>, <a class="reference internal" href="#_CPPv4N3fmt11format_argsE" title="fmt::format_args">format_args</a> <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt6vprintEPNSt4FILEE11string_view11format_args" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <section id="compile-time-format-string-checks"> <h3>Compile-Time Format String Checks<a class="headerlink" href="#compile-time-format-string-checks" title="Permalink to this headline">¶</a></h3> <p>Compile-time format string checks are enabled by default on compilers that support C++20 <code class="docutils literal notranslate"><span class="pre">consteval</span></code>. On older compilers you can use the <a class="reference internal" href="#legacy-checks"><span class="std std-ref">FMT_STRING</span></a>: macro defined in <code class="docutils literal notranslate"><span class="pre">fmt/format.h</span></code> instead.</p> <p>Unused arguments are allowed as in Python’s <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">str.format</span></code> and ordinary functions.</p> <dl class="cpp class"> <dt id="_CPPv4I0DpEN3fmt19basic_format_stringE"> <span id="_CPPv3I0DpEN3fmt19basic_format_stringE"></span><span id="_CPPv2I0DpEN3fmt19basic_format_stringE"></span>template<typename <code class="sig-name descname">Char</code>, typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="classfmt_1_1basic__format__string"></span><em class="property">class </em><code class="sig-name descname">basic_format_string</code><a class="headerlink" href="#_CPPv4I0DpEN3fmt19basic_format_stringE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>A compile-time format string. </p> </dd></dl> <dl class="cpp type"> <dt id="_CPPv4IDpEN3fmt13format_stringE"> <span id="_CPPv3IDpEN3fmt13format_stringE"></span><span id="_CPPv2IDpEN3fmt13format_stringE"></span>template<typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="core_8h_1a6151137b384766b8e3d283bcdbb05145"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_string</code> = <a class="reference internal" href="#_CPPv4I0DpEN3fmt19basic_format_stringE" title="fmt::basic_format_string">basic_format_string</a><char, type_identity_t<<a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string::Args">Args</a>>...><a class="headerlink" href="#_CPPv4IDpEN3fmt13format_stringE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt7runtimeE11string_view"> <span id="_CPPv3N3fmt7runtimeE11string_view"></span><span id="_CPPv2N3fmt7runtimeE11string_view"></span><span id="fmt::runtime__string_view"></span><span class="target" id="core_8h_1a5ebe213f4d505408abcfe01f5fa24c3b"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">runtime</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>s</em><span class="sig-paren">)</span> -> runtime_format_string<><a class="headerlink" href="#_CPPv4N3fmt7runtimeE11string_view" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Creates a runtime format string.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// Check format string at runtime instead of compile-time.</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="n">fmt</span><span class="o">::</span><span class="n">runtime</span><span class="p">(</span><span class="s">"{:d}"</span><span class="p">),</span><span class="w"> </span><span class="s">"I am not a number"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="formatting-user-defined-types"> <span id="udt"></span><h3>Formatting User-Defined Types<a class="headerlink" href="#formatting-user-defined-types" title="Permalink to this headline">¶</a></h3> <p>The {fmt} library provides formatters for many standard C++ types. See <a class="reference internal" href="#ranges-api"><span class="std std-ref">fmt/ranges.h</span></a> for ranges and tuples including standard containers such as <code class="docutils literal notranslate"><span class="pre">std::vector</span></code>, <a class="reference internal" href="#chrono-api"><span class="std std-ref">fmt/chrono.h</span></a> for date and time formatting and <a class="reference internal" href="#std-api"><span class="std std-ref">fmt/std.h</span></a> for other standard library types.</p> <p>There are two ways to make a user-defined type formattable: providing a <code class="docutils literal notranslate"><span class="pre">format_as</span></code> function or specializing the <code class="docutils literal notranslate"><span class="pre">formatter</span></code> struct template.</p> <p>Use <code class="docutils literal notranslate"><span class="pre">format_as</span></code> if you want to make your type formattable as some other type with the same format specifiers. The <code class="docutils literal notranslate"><span class="pre">format_as</span></code> function should take an object of your type and return an object of a formattable type. It should be defined in the same namespace as your type.</p> <p>Example (<a class="reference external" href="https://godbolt.org/z/nvME4arz8">https://godbolt.org/z/nvME4arz8</a>):</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> <span class="k">namespace</span><span class="w"> </span><span class="nn">kevin_namespacy</span><span class="w"> </span><span class="p">{</span> <span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">film</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">house_of_cards</span><span class="p">,</span><span class="w"> </span><span class="n">american_beauty</span><span class="p">,</span><span class="w"> </span><span class="n">se7en</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">7</span> <span class="p">};</span> <span class="k">auto</span><span class="w"> </span><span class="n">format_as</span><span class="p">(</span><span class="n">film</span><span class="w"> </span><span class="n">f</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">underlying</span><span class="p">(</span><span class="n">f</span><span class="p">);</span><span class="w"> </span><span class="p">}</span> <span class="p">}</span> <span class="kt">int</span><span class="w"> </span><span class="n">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span><span class="w"> </span><span class="n">kevin_namespacy</span><span class="o">::</span><span class="n">film</span><span class="o">::</span><span class="n">se7en</span><span class="p">);</span><span class="w"> </span><span class="c1">// prints "7"</span> <span class="p">}</span> </pre></div> </div> <p>Using specialization is more complex but gives you full control over parsing and formatting. To use this method specialize the <code class="docutils literal notranslate"><span class="pre">formatter</span></code> struct template for your type and implement <code class="docutils literal notranslate"><span class="pre">parse</span></code> and <code class="docutils literal notranslate"><span class="pre">format</span></code> methods.</p> <p>The recommended way of defining a formatter is by reusing an existing one via inheritance or composition. This way you can support standard format specifiers without implementing them yourself. For example:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// color.h:</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/core.h></span> <span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">color</span><span class="w"> </span><span class="p">{</span><span class="n">red</span><span class="p">,</span><span class="w"> </span><span class="n">green</span><span class="p">,</span><span class="w"> </span><span class="n">blue</span><span class="p">};</span> <span class="k">template</span><span class="w"> </span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">color</span><span class="o">>:</span><span class="w"> </span><span class="n">formatter</span><span class="o"><</span><span class="n">string_view</span><span class="o">></span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="c1">// parse is inherited from formatter<string_view>.</span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="n">color</span><span class="w"> </span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="n">format_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="p">;</span> <span class="p">};</span> <span class="c1">// color.cc:</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf">"color.h"</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> <span class="k">auto</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">color</span><span class="o">>::</span><span class="n">format</span><span class="p">(</span><span class="n">color</span><span class="w"> </span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="n">format_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">string_view</span><span class="w"> </span><span class="n">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"unknown"</span><span class="p">;</span> <span class="w"> </span><span class="k">switch</span><span class="w"> </span><span class="p">(</span><span class="n">c</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">color</span><span class="o">::</span><span class="no">red</span><span class="p">:</span><span class="w"> </span><span class="n">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"red"</span><span class="p">;</span><span class="w"> </span><span class="k">break</span><span class="p">;</span> <span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">color</span><span class="o">::</span><span class="no">green</span><span class="p">:</span><span class="w"> </span><span class="n">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"green"</span><span class="p">;</span><span class="w"> </span><span class="k">break</span><span class="p">;</span> <span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">color</span><span class="o">::</span><span class="no">blue</span><span class="p">:</span><span class="w"> </span><span class="n">name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"blue"</span><span class="p">;</span><span class="w"> </span><span class="k">break</span><span class="p">;</span> <span class="w"> </span><span class="p">}</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">formatter</span><span class="o"><</span><span class="n">string_view</span><span class="o">>::</span><span class="n">format</span><span class="p">(</span><span class="n">name</span><span class="p">,</span><span class="w"> </span><span class="n">ctx</span><span class="p">);</span> <span class="p">}</span> </pre></div> </div> <p>Note that <code class="docutils literal notranslate"><span class="pre">formatter<string_view>::format</span></code> is defined in <code class="docutils literal notranslate"><span class="pre">fmt/format.h</span></code> so it has to be included in the source file. Since <code class="docutils literal notranslate"><span class="pre">parse</span></code> is inherited from <code class="docutils literal notranslate"><span class="pre">formatter<string_view></span></code> it will recognize all string format specifications, for example</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:>10}"</span><span class="p">,</span><span class="w"> </span><span class="n">color</span><span class="o">::</span><span class="n">blue</span><span class="p">)</span> </pre></div> </div> <p>will return <code class="docutils literal notranslate"><span class="pre">"</span>      <span class="pre">blue"</span></code>.</p> <p>The experimental <code class="docutils literal notranslate"><span class="pre">nested_formatter</span></code> provides an easy way of applying a formatter to one or more subobjects.</p> <p>For example:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> <span class="k">struct</span><span class="w"> </span><span class="nc">point</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">x</span><span class="p">,</span><span class="w"> </span><span class="n">y</span><span class="p">;</span> <span class="p">};</span> <span class="k">template</span><span class="w"> </span><span class="o"><></span> <span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">point</span><span class="o">></span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">nested_formatter</span><span class="o"><</span><span class="kt">double</span><span class="o">></span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="n">point</span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n">format_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">write_padded</span><span class="p">(</span><span class="n">ctx</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="o">=</span><span class="p">](</span><span class="k">auto</span><span class="w"> </span><span class="n">out</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">format_to</span><span class="p">(</span><span class="n">out</span><span class="p">,</span><span class="w"> </span><span class="s">"({}, {})"</span><span class="p">,</span><span class="w"> </span><span class="n">nested</span><span class="p">(</span><span class="n">p</span><span class="p">.</span><span class="n">x</span><span class="p">),</span><span class="w"> </span><span class="n">nested</span><span class="p">(</span><span class="n">p</span><span class="p">.</span><span class="n">y</span><span class="p">));</span> <span class="w"> </span><span class="p">});</span> <span class="w"> </span><span class="p">}</span> <span class="p">};</span> <span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"[{:>20.2f}]"</span><span class="p">,</span><span class="w"> </span><span class="n">point</span><span class="p">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">});</span> <span class="p">}</span> </pre></div> </div> <p>prints:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="p">[</span><span class="w"> </span><span class="p">(</span><span class="mf">1.00</span><span class="p">,</span><span class="w"> </span><span class="mf">2.00</span><span class="p">)]</span> </pre></div> </div> <p>Notice that fill, align and width are applied to the whole object which is the recommended behavior while the remaining specifiers apply to elements.</p> <p>In general the formatter has the following form:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">template</span><span class="w"> </span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">T</span><span class="o">></span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="c1">// Parses format specifiers and stores them in the formatter.</span> <span class="w"> </span><span class="c1">//</span> <span class="w"> </span><span class="c1">// [ctx.begin(), ctx.end()) is a, possibly empty, character range that</span> <span class="w"> </span><span class="c1">// contains a part of the format string starting from the format</span> <span class="w"> </span><span class="c1">// specifications to be parsed, e.g. in</span> <span class="w"> </span><span class="c1">//</span> <span class="w"> </span><span class="c1">// fmt::format("{:f} continued", ...);</span> <span class="w"> </span><span class="c1">//</span> <span class="w"> </span><span class="c1">// the range will contain "f} continued". The formatter should parse</span> <span class="w"> </span><span class="c1">// specifiers until '}' or the end of the range. In this example the</span> <span class="w"> </span><span class="c1">// formatter should parse the 'f' specifier and return an iterator</span> <span class="w"> </span><span class="c1">// pointing to '}'.</span> <span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">parse</span><span class="p">(</span><span class="n">format_parse_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span> <span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">format_parse_context</span><span class="o">::</span><span class="n">iterator</span><span class="p">;</span> <span class="w"> </span><span class="c1">// Formats value using the parsed format specification stored in this</span> <span class="w"> </span><span class="c1">// formatter and writes the output to ctx.out().</span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">T</span><span class="o">&</span><span class="w"> </span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="n">format_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span> <span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">format_context</span><span class="o">::</span><span class="n">iterator</span><span class="p">;</span> <span class="p">};</span> </pre></div> </div> <p>It is recommended to at least support fill, align and width that apply to the whole object and have the same semantics as in standard formatters.</p> <p>You can also write a formatter for a hierarchy of classes:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// demo.h:</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><type_traits></span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/core.h></span> <span class="k">struct</span><span class="w"> </span><span class="nc">A</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">virtual</span><span class="w"> </span><span class="o">~</span><span class="n">A</span><span class="p">()</span><span class="w"> </span><span class="p">{}</span> <span class="w"> </span><span class="k">virtual</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">name</span><span class="p">()</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"A"</span><span class="p">;</span><span class="w"> </span><span class="p">}</span> <span class="p">};</span> <span class="k">struct</span><span class="w"> </span><span class="nc">B</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">A</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">virtual</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="nf">name</span><span class="p">()</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"B"</span><span class="p">;</span><span class="w"> </span><span class="p">}</span> <span class="p">};</span> <span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">typename</span><span class="w"> </span><span class="nc">T</span><span class="o">></span> <span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">enable_if_t</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">is_base_of</span><span class="o"><</span><span class="n">A</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="o">>::</span><span class="n">value</span><span class="p">,</span><span class="w"> </span><span class="kt">char</span><span class="o">>></span><span class="w"> </span><span class="o">:</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">A</span><span class="o">&</span><span class="w"> </span><span class="n">a</span><span class="p">,</span><span class="w"> </span><span class="n">format_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">>::</span><span class="n">format</span><span class="p">(</span><span class="n">a</span><span class="p">.</span><span class="n">name</span><span class="p">(),</span><span class="w"> </span><span class="n">ctx</span><span class="p">);</span> <span class="w"> </span><span class="p">}</span> <span class="p">};</span> <span class="c1">// demo.cc:</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf">"demo.h"</span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> <span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">B</span><span class="w"> </span><span class="n">b</span><span class="p">;</span> <span class="w"> </span><span class="n">A</span><span class="o">&</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">b</span><span class="p">;</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">a</span><span class="p">);</span><span class="w"> </span><span class="c1">// prints "B"</span> <span class="p">}</span> </pre></div> </div> <p>Providing both a <code class="docutils literal notranslate"><span class="pre">formatter</span></code> specialization and a <code class="docutils literal notranslate"><span class="pre">format_as</span></code> overload is disallowed.</p> </section> <section id="named-arguments"> <h3>Named Arguments<a class="headerlink" href="#named-arguments" title="Permalink to this headline">¶</a></h3> <dl class="cpp function"> <dt id="_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T"> <span id="_CPPv3I00EN3fmt3argEPK4CharRK1T"></span><span id="_CPPv2I00EN3fmt3argEPK4CharRK1T"></span>template<typename <code class="sig-name descname">Char</code>, typename <code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1a0186a488c80ab72f718b8d001960b1e9"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">arg</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg::Char">Char</a> *<em>name</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg::T">T</a> &<em>arg</em><span class="sig-paren">)</span> -> detail::named_arg<<a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg::Char">Char</a>, <a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg::T">T</a>><a class="headerlink" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Returns a named argument to be used in a formatting function. It should only be used in a call to a formatting function or <a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRK1T" title="fmt::dynamic_format_arg_store::push_back"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">dynamic_format_arg_store::push_back()</span></code></a>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Elapsed time: {s:.2f} seconds"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">arg</span><span class="p">(</span><span class="s">"s"</span><span class="p">,</span><span class="w"> </span><span class="mf">1.23</span><span class="p">));</span> </pre></div> </div> </p> </p> </dd></dl> <p>Named arguments are not supported in compile-time checks at the moment.</p> </section> <section id="argument-lists"> <h3>Argument Lists<a class="headerlink" href="#argument-lists" title="Permalink to this headline">¶</a></h3> <p>You can create your own formatting function with compile-time checks and small binary footprint, for example (<a class="reference external" href="https://godbolt.org/z/vajfWEG4b">https://godbolt.org/z/vajfWEG4b</a>):</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/core.h></span> <span class="kt">void</span><span class="w"> </span><span class="nf">vlog</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">line</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">string_view</span><span class="w"> </span><span class="n">format</span><span class="p">,</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format_args</span><span class="w"> </span><span class="n">args</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}: {}: "</span><span class="p">,</span><span class="w"> </span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="n">line</span><span class="p">);</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">vprint</span><span class="p">(</span><span class="n">format</span><span class="p">,</span><span class="w"> </span><span class="n">args</span><span class="p">);</span> <span class="p">}</span> <span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">typename</span><span class="p">...</span><span class="w"> </span><span class="n">T</span><span class="o">></span> <span class="kt">void</span><span class="w"> </span><span class="n">log</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">line</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format_string</span><span class="o"><</span><span class="n">T</span><span class="p">...</span><span class="o">></span><span class="w"> </span><span class="n">format</span><span class="p">,</span><span class="w"> </span><span class="n">T</span><span class="o">&&</span><span class="p">...</span><span class="w"> </span><span class="n">args</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">vlog</span><span class="p">(</span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="n">line</span><span class="p">,</span><span class="w"> </span><span class="n">format</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">make_format_args</span><span class="p">(</span><span class="n">args</span><span class="p">...));</span> <span class="p">}</span> <span class="cp">#define MY_LOG(format, ...) log(__FILE__, __LINE__, format, __VA_ARGS__)</span> <span class="n">MY_LOG</span><span class="p">(</span><span class="s">"invalid squishiness: {}"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> <p>Note that <code class="docutils literal notranslate"><span class="pre">vlog</span></code> is not parameterized on argument types which improves compile times and reduces binary code size compared to a fully parameterized version.</p> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T"> <span id="_CPPv3I0DpEN3fmt16make_format_argsEDpR1T"></span><span id="_CPPv2I0DpEN3fmt16make_format_argsEDpR1T"></span>template<typename <code class="sig-name descname">Context</code> = <a class="reference internal" href="#_CPPv4N3fmt14format_contextE" title="fmt::format_context">format_context</a>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="core_8h_1ae17debf20cdb02049729e0db732ea89a"></span><em class="property">constexpr</em> auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">make_format_args</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T" title="fmt::make_format_args::T">T</a>&... <em>args</em><span class="sig-paren">)</span> -> <a class="reference internal" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="fmt::format_arg_store">format_arg_store</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T" title="fmt::make_format_args::Context">Context</a>, remove_cvref_t<<a class="reference internal" href="#_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T" title="fmt::make_format_args::T">T</a>>...><a class="headerlink" href="#_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <a class="reference internal" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="fmt::format_arg_store"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_arg_store</span></code></a> object that contains references to arguments and can be implicitly converted to <a class="reference internal" href="#_CPPv4N3fmt11format_argsE" title="fmt::format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_args</span></code></a>. <a class="reference internal" href="#_CPPv4I0DpEN3fmt16make_format_argsE16format_arg_storeI7ContextDp14remove_cvref_tI1TEEDpR1T" title="fmt::make_format_args::Context"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">Context</span></code></a> can be omitted in which case it defaults to <a class="reference internal" href="#_CPPv4N3fmt14format_contextE" title="fmt::format_context"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_context</span></code></a>. See <a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">arg()</span></code></a> for lifetime considerations.</p> </p> </p> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0DpEN3fmt16format_arg_storeE"> <span id="_CPPv3I0DpEN3fmt16format_arg_storeE"></span><span id="_CPPv2I0DpEN3fmt16format_arg_storeE"></span>template<typename <code class="sig-name descname">Context</code>, typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="classfmt_1_1format__arg__store"></span><em class="property">class </em><code class="sig-name descname">format_arg_store</code><a class="headerlink" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>An array of references to arguments. It can be implicitly converted into <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="fmt::basic_format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_format_args</span></code></a> for passing into type-erased formatting functions such as <a class="reference internal" href="#_CPPv4N3fmt7vformatE11string_view11format_args" title="fmt::vformat"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">vformat()</span></code></a>.</p> </p> </p> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt17basic_format_argsE"> <span id="_CPPv3I0EN3fmt17basic_format_argsE"></span><span id="_CPPv2I0EN3fmt17basic_format_argsE"></span>template<typename <code class="sig-name descname">Context</code>><br /><span class="target" id="classfmt_1_1basic__format__args"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">basic_format_args</code><a class="headerlink" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>A view of a collection of formatting arguments. To avoid lifetime issues it should only be used as a parameter type in type-erased functions such as <code class="docutils literal notranslate"><span class="pre">vformat</span></code>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span><span class="w"> </span><span class="nf">vlog</span><span class="p">(</span><span class="n">string_view</span><span class="w"> </span><span class="n">format_str</span><span class="p">,</span><span class="w"> </span><span class="n">format_args</span><span class="w"> </span><span class="n">args</span><span class="p">);</span><span class="w"> </span><span class="c1">// OK</span> <span class="n">format_args</span><span class="w"> </span><span class="n">args</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">make_format_args</span><span class="p">();</span><span class="w"> </span><span class="c1">// Error: dangling reference</span> </pre></div> </div> </p> </p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE"> <span id="_CPPv3IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE"></span><span id="_CPPv2IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE"></span>template<typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="classfmt_1_1basic__format__args_1aa29b9df6b51427157eb9c4881a12cc19"></span><em class="property">constexpr</em> <code class="sig-name descname">basic_format_args</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="fmt::format_arg_store">format_arg_store</a><<a class="reference internal" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="fmt::basic_format_args::Context">Context</a>, <a class="reference internal" href="#_CPPv4IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE" title="fmt::basic_format_args::basic_format_args::Args">Args</a>...> &<em>store</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <a class="reference internal" href="#_CPPv4IDpEN3fmt17basic_format_args17basic_format_argsERK16format_arg_storeI7ContextDp4ArgsE" title="fmt::basic_format_args::basic_format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_format_args()</span></code></a> object from <a class="reference internal" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="fmt::format_arg_store"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">format_arg_store</span></code></a>.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt17basic_format_args17basic_format_argsERK24dynamic_format_arg_storeI7ContextE"> <span id="_CPPv3N3fmt17basic_format_args17basic_format_argsERK24dynamic_format_arg_storeI7ContextE"></span><span id="_CPPv2N3fmt17basic_format_args17basic_format_argsERK24dynamic_format_arg_storeI7ContextE"></span><span id="fmt::basic_format_args::basic_format_args__dynamic_format_arg_store:Context:CRCE"></span><span class="target" id="classfmt_1_1basic__format__args_1a9708feb267c220363a56f82348cd3809"></span><em class="property">constexpr</em> <code class="sig-name descname">basic_format_args</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_storeE" title="fmt::dynamic_format_arg_store">dynamic_format_arg_store</a><<a class="reference internal" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="fmt::basic_format_args::Context">Context</a>> &<em>store</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt17basic_format_args17basic_format_argsERK24dynamic_format_arg_storeI7ContextE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <a class="reference internal" href="#_CPPv4N3fmt17basic_format_args17basic_format_argsERK24dynamic_format_arg_storeI7ContextE" title="fmt::basic_format_args::basic_format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_format_args()</span></code></a> object from <a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_storeE" title="fmt::dynamic_format_arg_store"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">dynamic_format_arg_store</span></code></a>.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt17basic_format_args17basic_format_argsEPK10format_argi"> <span id="_CPPv3N3fmt17basic_format_args17basic_format_argsEPK10format_argi"></span><span id="_CPPv2N3fmt17basic_format_args17basic_format_argsEPK10format_argi"></span><span id="fmt::basic_format_args::basic_format_args__format_argCP.iCE"></span><span class="target" id="classfmt_1_1basic__format__args_1abd2d437108168771b2cbbf947c84d9c1"></span><em class="property">constexpr</em> <code class="sig-name descname">basic_format_args</code><span class="sig-paren">(</span><em class="property">const</em> format_arg *<em>args</em>, int <em>count</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt17basic_format_args17basic_format_argsEPK10format_argi" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <a class="reference internal" href="#_CPPv4N3fmt17basic_format_args17basic_format_argsEPK10format_argi" title="fmt::basic_format_args::basic_format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_format_args()</span></code></a> object from a dynamic set of arguments.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4NK3fmt17basic_format_args3getEi"> <span id="_CPPv3NK3fmt17basic_format_args3getEi"></span><span id="_CPPv2NK3fmt17basic_format_args3getEi"></span><span id="fmt::basic_format_args::get__iC"></span><span class="target" id="classfmt_1_1basic__format__args_1a4714316d66a0c30e5bd3faf9c695b4f0"></span>auto <code class="sig-name descname">get</code><span class="sig-paren">(</span>int <em>id</em><span class="sig-paren">)</span> <em class="property">const</em> -> format_arg<a class="headerlink" href="#_CPPv4NK3fmt17basic_format_args3getEi" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns the argument with the specified id. </p> </dd></dl> </div> </dd></dl> <dl class="cpp type"> <dt id="_CPPv4N3fmt11format_argsE"> <span id="_CPPv3N3fmt11format_argsE"></span><span id="_CPPv2N3fmt11format_argsE"></span><span class="target" id="core_8h_1a2f47e63581cb37cd6377edce1d6cb131"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_args</code> = <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="fmt::basic_format_args">basic_format_args</a><<a class="reference internal" href="#_CPPv4N3fmt14format_contextE" title="fmt::format_context">format_context</a>><a class="headerlink" href="#_CPPv4N3fmt11format_argsE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>An alias to <code class="docutils literal notranslate"><span class="pre">basic_format_args<format_context></span></code>. </p> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt16basic_format_argE"> <span id="_CPPv3I0EN3fmt16basic_format_argE"></span><span id="_CPPv2I0EN3fmt16basic_format_argE"></span>template<typename <code class="sig-name descname">Context</code>><br /><span class="target" id="classfmt_1_1basic__format__arg"></span><em class="property">class </em><code class="sig-name descname">basic_format_arg</code><a class="headerlink" href="#_CPPv4I0EN3fmt16basic_format_argE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt26basic_format_parse_contextE"> <span id="_CPPv3I0EN3fmt26basic_format_parse_contextE"></span><span id="_CPPv2I0EN3fmt26basic_format_parse_contextE"></span>template<typename <code class="sig-name descname">Char</code>><br /><span class="target" id="classfmt_1_1basic__format__parse__context"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">basic_format_parse_context</code><a class="headerlink" href="#_CPPv4I0EN3fmt26basic_format_parse_contextE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Parsing context consisting of a format string range being parsed and an argument counter for automatic indexing. You can use the <code class="docutils literal notranslate"><span class="pre">format_parse_context</span></code> type alias for <code class="docutils literal notranslate"><span class="pre">char</span></code> instead.</p> </p> </p> <p>Subclassed by fmt::detail::compile_parse_context< Char ></p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4NK3fmt26basic_format_parse_context5beginEv"> <span id="_CPPv3NK3fmt26basic_format_parse_context5beginEv"></span><span id="_CPPv2NK3fmt26basic_format_parse_context5beginEv"></span><span id="fmt::basic_format_parse_context::beginCCE"></span><span class="target" id="classfmt_1_1basic__format__parse__context_1aa830187d6c59f36a4641ca53e8aa6968"></span><em class="property">constexpr</em> auto <code class="sig-name descname">begin</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> iterator<a class="headerlink" href="#_CPPv4NK3fmt26basic_format_parse_context5beginEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns an iterator to the beginning of the format string range being parsed. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4NK3fmt26basic_format_parse_context3endEv"> <span id="_CPPv3NK3fmt26basic_format_parse_context3endEv"></span><span id="_CPPv2NK3fmt26basic_format_parse_context3endEv"></span><span id="fmt::basic_format_parse_context::endCCE"></span><span class="target" id="classfmt_1_1basic__format__parse__context_1aeabda8d18f88e74f251526131778d7fb"></span><em class="property">constexpr</em> auto <code class="sig-name descname">end</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> iterator<a class="headerlink" href="#_CPPv4NK3fmt26basic_format_parse_context3endEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns an iterator past the end of the format string range being parsed. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt26basic_format_parse_context10advance_toE8iterator"> <span id="_CPPv3N3fmt26basic_format_parse_context10advance_toE8iterator"></span><span id="_CPPv2N3fmt26basic_format_parse_context10advance_toE8iterator"></span><span id="fmt::basic_format_parse_context::advance_to__iterator"></span><span class="target" id="classfmt_1_1basic__format__parse__context_1ae3aad50336bd6a39a5b12604e4817a48"></span>void <code class="sig-name descname">advance_to</code><span class="sig-paren">(</span>iterator <em>it</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt26basic_format_parse_context10advance_toE8iterator" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Advances the begin iterator to <code class="docutils literal notranslate"><span class="pre">it</span></code>. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt26basic_format_parse_context11next_arg_idEv"> <span id="_CPPv3N3fmt26basic_format_parse_context11next_arg_idEv"></span><span id="_CPPv2N3fmt26basic_format_parse_context11next_arg_idEv"></span><span id="fmt::basic_format_parse_context::next_arg_id"></span><span class="target" id="classfmt_1_1basic__format__parse__context_1a5b7a4d2df94eb76fe99332ded3a8ff5e"></span>auto <code class="sig-name descname">next_arg_id</code><span class="sig-paren">(</span><span class="sig-paren">)</span> -> int<a class="headerlink" href="#_CPPv4N3fmt26basic_format_parse_context11next_arg_idEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Reports an error if using the manual argument indexing; otherwise returns the next argument index and switches to the automatic indexing. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt26basic_format_parse_context12check_arg_idEi"> <span id="_CPPv3N3fmt26basic_format_parse_context12check_arg_idEi"></span><span id="_CPPv2N3fmt26basic_format_parse_context12check_arg_idEi"></span><span id="fmt::basic_format_parse_context::check_arg_id__i"></span><span class="target" id="classfmt_1_1basic__format__parse__context_1a0978f2b02767da8f4b6e082c52ec631c"></span>void <code class="sig-name descname">check_arg_id</code><span class="sig-paren">(</span>int <em>id</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt26basic_format_parse_context12check_arg_idEi" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Reports an error if using the automatic argument indexing; otherwise switches to the manual indexing. </p> </dd></dl> </div> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I00EN3fmt20basic_format_contextE"> <span id="_CPPv3I00EN3fmt20basic_format_contextE"></span><span id="_CPPv2I00EN3fmt20basic_format_contextE"></span>template<typename <code class="sig-name descname">OutputIt</code>, typename <code class="sig-name descname">Char</code>><br /><span class="target" id="classfmt_1_1basic__format__context"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">basic_format_context</code><a class="headerlink" href="#_CPPv4I00EN3fmt20basic_format_contextE" title="Permalink to this definition">¶</a><br /></dt> <dd><div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Types</p> <dl class="cpp type"> <dt id="_CPPv4N3fmt20basic_format_context9char_typeE"> <span id="_CPPv3N3fmt20basic_format_context9char_typeE"></span><span id="_CPPv2N3fmt20basic_format_context9char_typeE"></span><span class="target" id="classfmt_1_1basic__format__context_1a2d6b20e51d17975188e4463cd3b681ae"></span><em class="property">using </em><code class="sig-name descname">char_type</code> = <a class="reference internal" href="#_CPPv4I00EN3fmt20basic_format_contextE" title="fmt::basic_format_context::Char">Char</a><a class="headerlink" href="#_CPPv4N3fmt20basic_format_context9char_typeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>The character type for the output. </p> </dd></dl> </div> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4N3fmt20basic_format_context20basic_format_contextE8OutputIt11format_argsN6detail10locale_refE"> <span id="_CPPv3N3fmt20basic_format_context20basic_format_contextE8OutputIt11format_argsN6detail10locale_refE"></span><span id="_CPPv2N3fmt20basic_format_context20basic_format_contextE8OutputIt11format_argsN6detail10locale_refE"></span><span id="fmt::basic_format_context::basic_format_context__OutputIt.format_args.detail::locale_refCE"></span><span class="target" id="classfmt_1_1basic__format__context_1ab32a6df3da0f1f4e2ff8188d1e21e0be"></span><em class="property">constexpr</em> <code class="sig-name descname">basic_format_context</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I00EN3fmt20basic_format_contextE" title="fmt::basic_format_context::OutputIt">OutputIt</a> <em>out</em>, <a class="reference internal" href="#_CPPv4N3fmt11format_argsE" title="fmt::format_args">format_args</a> <em>ctx_args</em>, detail::locale_ref <em>loc</em> = {}<span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt20basic_format_context20basic_format_contextE8OutputIt11format_argsN6detail10locale_refE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Constructs a <code class="docutils literal notranslate"><span class="pre">basic_format_context</span></code> object. </p> <p>References to the arguments are stored in the object so make sure they have appropriate lifetimes. </p> </dd></dl> </div> </dd></dl> <dl class="cpp type"> <dt id="_CPPv4N3fmt14format_contextE"> <span id="_CPPv3N3fmt14format_contextE"></span><span id="_CPPv2N3fmt14format_contextE"></span><span class="target" id="core_8h_1a467d4e330ff42661b03cceaed5a6dfc8"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_context</code> = buffer_context<char><a class="headerlink" href="#_CPPv4N3fmt14format_contextE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> </section> <section id="dynamic-argument-lists"> <span id="args-api"></span><h3>Dynamic Argument Lists<a class="headerlink" href="#dynamic-argument-lists" title="Permalink to this headline">¶</a></h3> <p>The header <code class="docutils literal notranslate"><span class="pre">fmt/args.h</span></code> provides <code class="docutils literal notranslate"><span class="pre">dynamic_format_arg_store</span></code>, a builder-like API that can be used to construct format argument lists dynamically.</p> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt24dynamic_format_arg_storeE"> <span id="_CPPv3I0EN3fmt24dynamic_format_arg_storeE"></span><span id="_CPPv2I0EN3fmt24dynamic_format_arg_storeE"></span>template<typename <code class="sig-name descname">Context</code>><br /><span class="target" id="classfmt_1_1dynamic__format__arg__store"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">dynamic_format_arg_store</code><a class="headerlink" href="#_CPPv4I0EN3fmt24dynamic_format_arg_storeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>A dynamic version of <a class="reference internal" href="#_CPPv4I0DpEN3fmt16format_arg_storeE" title="fmt::format_arg_store"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">fmt::format_arg_store</span></code></a>. It’s equipped with a storage to potentially temporary objects which lifetimes could be shorter than the format arguments object.</p> <p>It can be implicitly converted into <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_format_argsE" title="fmt::basic_format_args"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_format_args</span></code></a> for passing into type-erased formatting functions such as <a class="reference internal" href="#_CPPv4N3fmt7vformatE11string_view11format_args" title="fmt::vformat"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">vformat()</span></code></a>.</p> </p> </p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRK1T"> <span id="_CPPv3I0EN3fmt24dynamic_format_arg_store9push_backERK1T"></span><span id="_CPPv2I0EN3fmt24dynamic_format_arg_store9push_backERK1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1dynamic__format__arg__store_1af3020ec9bf9450a1d6020be9a19f70d3"></span>void <code class="sig-name descname">push_back</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRK1T" title="fmt::dynamic_format_arg_store::push_back::T">T</a> &<em>arg</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Adds an argument into the dynamic store for later passing to a formatting function.</p> <p>Note that custom types and string types (but not string views) are copied into the store dynamically allocating memory if necessary.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">dynamic_format_arg_store</span><span class="o"><</span><span class="n">fmt</span><span class="o">::</span><span class="n">format_context</span><span class="o">></span><span class="w"> </span><span class="n">store</span><span class="p">;</span> <span class="n">store</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="mi">42</span><span class="p">);</span> <span class="n">store</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="s">"abc"</span><span class="p">);</span> <span class="n">store</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="mf">1.5f</span><span class="p">);</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">vformat</span><span class="p">(</span><span class="s">"{} and {} and {}"</span><span class="p">,</span><span class="w"> </span><span class="n">store</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvNSt17reference_wrapperI1TEE"> <span id="_CPPv3I0EN3fmt24dynamic_format_arg_store9push_backENSt17reference_wrapperI1TEE"></span><span id="_CPPv2I0EN3fmt24dynamic_format_arg_store9push_backENSt17reference_wrapperI1TEE"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1dynamic__format__arg__store_1a858e191df4feee6a7796744a6d8182f5"></span>void <code class="sig-name descname">push_back</code><span class="sig-paren">(</span>std::reference_wrapper<<a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvNSt17reference_wrapperI1TEE" title="fmt::dynamic_format_arg_store::push_back::T">T</a>> <em>arg</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvNSt17reference_wrapperI1TEE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Adds a reference to the argument into the dynamic store for later passing to a formatting function.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">dynamic_format_arg_store</span><span class="o"><</span><span class="n">fmt</span><span class="o">::</span><span class="n">format_context</span><span class="o">></span><span class="w"> </span><span class="n">store</span><span class="p">;</span> <span class="kt">char</span><span class="w"> </span><span class="n">band</span><span class="p">[]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"Rolling Stones"</span><span class="p">;</span> <span class="n">store</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">cref</span><span class="p">(</span><span class="n">band</span><span class="p">));</span> <span class="n">band</span><span class="p">[</span><span class="mi">9</span><span class="p">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sc">'c'</span><span class="p">;</span><span class="w"> </span><span class="c1">// Changing str affects the output.</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">vformat</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">store</span><span class="p">);</span> <span class="c1">// result == "Rolling Scones"</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRKN6detail9named_argI9char_type1TEE"> <span id="_CPPv3I0EN3fmt24dynamic_format_arg_store9push_backERKN6detail9named_argI9char_type1TEE"></span><span id="_CPPv2I0EN3fmt24dynamic_format_arg_store9push_backERKN6detail9named_argI9char_type1TEE"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1dynamic__format__arg__store_1a55ca65d17f91face9f22e1d23097f94f"></span>void <code class="sig-name descname">push_back</code><span class="sig-paren">(</span><em class="property">const</em> detail::named_arg<char_type, <a class="reference internal" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRKN6detail9named_argI9char_type1TEE" title="fmt::dynamic_format_arg_store::push_back::T">T</a>> &<em>arg</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I0EN3fmt24dynamic_format_arg_store9push_backEvRKN6detail9named_argI9char_type1TEE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Adds named argument into the dynamic store for later passing to a formatting function. </p> <p><code class="docutils literal notranslate"><span class="pre">std::reference_wrapper</span></code> is supported to avoid copying of the argument. The name is always copied into the store. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt24dynamic_format_arg_store5clearEv"> <span id="_CPPv3N3fmt24dynamic_format_arg_store5clearEv"></span><span id="_CPPv2N3fmt24dynamic_format_arg_store5clearEv"></span><span id="fmt::dynamic_format_arg_store::clear"></span><span class="target" id="classfmt_1_1dynamic__format__arg__store_1ab675b3a51c36b3c07b7f3acb68693dff"></span>void <code class="sig-name descname">clear</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt24dynamic_format_arg_store5clearEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Erase all elements from the store. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt24dynamic_format_arg_store7reserveE6size_t6size_t"> <span id="_CPPv3N3fmt24dynamic_format_arg_store7reserveE6size_t6size_t"></span><span id="_CPPv2N3fmt24dynamic_format_arg_store7reserveE6size_t6size_t"></span><span id="fmt::dynamic_format_arg_store::reserve__s.s"></span><span class="target" id="classfmt_1_1dynamic__format__arg__store_1a86fb8989b4b8a225db5ec1037f534128"></span>void <code class="sig-name descname">reserve</code><span class="sig-paren">(</span>size_t <em>new_cap</em>, size_t <em>new_cap_named</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt24dynamic_format_arg_store7reserveE6size_t6size_t" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Reserves space to store at least <em>new_cap</em> arguments including <em>new_cap_named</em> named arguments.</p> </p> </p> </dd></dl> </div> </dd></dl> </section> <section id="compatibility"> <h3>Compatibility<a class="headerlink" href="#compatibility" title="Permalink to this headline">¶</a></h3> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt17basic_string_viewE"> <span id="_CPPv3I0EN3fmt17basic_string_viewE"></span><span id="_CPPv2I0EN3fmt17basic_string_viewE"></span>template<typename <code class="sig-name descname">Char</code>><br /><span class="target" id="classfmt_1_1basic__string__view"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">basic_string_view</code><a class="headerlink" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>An implementation of <code class="docutils literal notranslate"><span class="pre">std::basic_string_view</span></code> for pre-C++17. </p> <p>It provides a subset of the API. <code class="docutils literal notranslate"><span class="pre">fmt::basic_string_view</span></code> is used for format strings even if <code class="docutils literal notranslate"><span class="pre">std::string_view</span></code> is available to prevent issues when a library is compiled with a different <code class="docutils literal notranslate"><span class="pre">-std</span></code> option than the client code (which is not recommended). </p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4N3fmt17basic_string_view17basic_string_viewEPK4Char6size_t"> <span id="_CPPv3N3fmt17basic_string_view17basic_string_viewEPK4Char6size_t"></span><span id="_CPPv2N3fmt17basic_string_view17basic_string_viewEPK4Char6size_t"></span><span id="fmt::basic_string_view::basic_string_view__CharCP.sCE"></span><span class="target" id="classfmt_1_1basic__string__view_1a77724577d4a659ea5a1080abe63d847d"></span><em class="property">constexpr</em> <code class="sig-name descname">basic_string_view</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view::Char">Char</a> *<em>s</em>, size_t <em>count</em><span class="sig-paren">)</span> <em class="property">noexcept</em><a class="headerlink" href="#_CPPv4N3fmt17basic_string_view17basic_string_viewEPK4Char6size_t" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Constructs a string reference object from a C string and a size. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt17basic_string_view17basic_string_viewEPK4Char"> <span id="_CPPv3N3fmt17basic_string_view17basic_string_viewEPK4Char"></span><span id="_CPPv2N3fmt17basic_string_view17basic_string_viewEPK4Char"></span><span id="fmt::basic_string_view::basic_string_view__CharCP"></span><span class="target" id="classfmt_1_1basic__string__view_1a027c1e3a6352aa4ad89a1414bbf1c349"></span><code class="sig-name descname">basic_string_view</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view::Char">Char</a> *<em>s</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt17basic_string_view17basic_string_viewEPK4Char" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a string reference object from a C string computing the size with <code class="docutils literal notranslate"><span class="pre">std::char_traits<Char>::length</span></code>.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE"> <span id="_CPPv3I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE"></span><span id="_CPPv2I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE"></span>template<typename <code class="sig-name descname">Traits</code>, typename <code class="sig-name descname">Alloc</code>><br /><span class="target" id="classfmt_1_1basic__string__view_1af12a79eae6c2cecea40e52cb193c7608"></span><code class="sig-name descname">basic_string_view</code><span class="sig-paren">(</span><em class="property">const</em> std::basic_string<<a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view::Char">Char</a>, <a class="reference internal" href="#_CPPv4I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE" title="fmt::basic_string_view::basic_string_view::Traits">Traits</a>, <a class="reference internal" href="#_CPPv4I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE" title="fmt::basic_string_view::basic_string_view::Alloc">Alloc</a>> &<em>s</em><span class="sig-paren">)</span> <em class="property">noexcept</em><a class="headerlink" href="#_CPPv4I00EN3fmt17basic_string_view17basic_string_viewERKNSt12basic_stringI4Char6Traits5AllocEE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Constructs a string reference from a <code class="docutils literal notranslate"><span class="pre">std::basic_string</span></code> object. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4NK3fmt17basic_string_view4dataEv"> <span id="_CPPv3NK3fmt17basic_string_view4dataEv"></span><span id="_CPPv2NK3fmt17basic_string_view4dataEv"></span><span id="fmt::basic_string_view::dataCCE"></span><span class="target" id="classfmt_1_1basic__string__view_1a358b32b01d47dfdf17b0f6ff3f8bbe4f"></span><em class="property">constexpr</em> auto <code class="sig-name descname">data</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view::Char">Char</a>*<a class="headerlink" href="#_CPPv4NK3fmt17basic_string_view4dataEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns a pointer to the string data. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4NK3fmt17basic_string_view4sizeEv"> <span id="_CPPv3NK3fmt17basic_string_view4sizeEv"></span><span id="_CPPv2NK3fmt17basic_string_view4sizeEv"></span><span id="fmt::basic_string_view::sizeCCE"></span><span class="target" id="classfmt_1_1basic__string__view_1a52d7307059832543f7288803ca78dcbc"></span><em class="property">constexpr</em> auto <code class="sig-name descname">size</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> size_t<a class="headerlink" href="#_CPPv4NK3fmt17basic_string_view4sizeEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns the string size. </p> </dd></dl> </div> </dd></dl> <dl class="cpp type"> <dt id="_CPPv4N3fmt11string_viewE"> <span id="_CPPv3N3fmt11string_viewE"></span><span id="_CPPv2N3fmt11string_viewE"></span><span class="target" id="core_8h_1ac884b6d263af5b3c1b711ee568225364"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">string_view</code> = <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view">basic_string_view</a><char><a class="headerlink" href="#_CPPv4N3fmt11string_viewE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> </section> </section> <section id="format-api"> <span id="id2"></span><h2>Format API<a class="headerlink" href="#format-api" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/format.h</span></code> defines the full format API providing additional formatting functions and locale support.</p> <section id="literal-based-api"> <h3>Literal-Based API<a class="headerlink" href="#literal-based-api" title="Permalink to this headline">¶</a></h3> <p>The following user-defined literals are defined in <code class="docutils literal notranslate"><span class="pre">fmt/format.h</span></code>.</p> <dl class="cpp function"> <dt id="_CPPv4I_N15detail_exported12fixed_stringEEN3fmtli2_aEDav"> <span id="_CPPv3I_N15detail_exported12fixed_stringEEN3fmtli2_aEv"></span><span id="_CPPv2I_N15detail_exported12fixed_stringEEN3fmtli2_aEv"></span>template<detail_exported::fixed_string <code class="sig-name descname">Str</code>><br /><span class="target" id="format_8h_1a61cae931a86f3a5891edf0ff838fee3a"></span><em class="property">constexpr</em> auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">operator""_a</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I_N15detail_exported12fixed_stringEEN3fmtli2_aEDav" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>User-defined literal equivalent of <a class="reference internal" href="#_CPPv4I00EN3fmt3argEN6detail9named_argI4Char1TEEPK4CharRK1T" title="fmt::arg"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">fmt::arg()</span></code></a>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">using</span><span class="w"> </span><span class="k">namespace</span><span class="w"> </span><span class="nn">fmt</span><span class="o">::</span><span class="nn">literals</span><span class="p">;</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Elapsed time: {s:.2f} seconds"</span><span class="p">,</span><span class="w"> </span><span class="s">"s"</span><span class="n">_a</span><span class="o">=</span><span class="mf">1.23</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="utilities"> <h3>Utilities<a class="headerlink" href="#utilities" title="Permalink to this headline">¶</a></h3> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt3ptrEPKv1T"> <span id="_CPPv3I0EN3fmt3ptrE1T"></span><span id="_CPPv2I0EN3fmt3ptrE1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1ac62203b4bde2a7a7e3a3ef05c33f8675"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">ptr</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0EN3fmt3ptrEPKv1T" title="fmt::ptr::T">T</a> <em>p</em><span class="sig-paren">)</span> -> <em class="property">const</em> void*<a class="headerlink" href="#_CPPv4I0EN3fmt3ptrEPKv1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Converts <code class="docutils literal notranslate"><span class="pre">p</span></code> to <code class="docutils literal notranslate"><span class="pre">const</span> <span class="pre">void*</span></code> for pointer formatting.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">ptr</span><span class="p">(</span><span class="n">p</span><span class="p">));</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I00EN3fmt3ptrEPKvRKNSt10unique_ptrI1T7DeleterEE"> <span id="_CPPv3I00EN3fmt3ptrERKNSt10unique_ptrI1T7DeleterEE"></span><span id="_CPPv2I00EN3fmt3ptrERKNSt10unique_ptrI1T7DeleterEE"></span>template<typename <code class="sig-name descname">T</code>, typename <code class="sig-name descname">Deleter</code>><br /><span class="target" id="format_8h_1a53e1e7c78e3118e81c59f07ec602a6e2"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">ptr</code><span class="sig-paren">(</span><em class="property">const</em> std::unique_ptr<<a class="reference internal" href="#_CPPv4I00EN3fmt3ptrEPKvRKNSt10unique_ptrI1T7DeleterEE" title="fmt::ptr::T">T</a>, <a class="reference internal" href="#_CPPv4I00EN3fmt3ptrEPKvRKNSt10unique_ptrI1T7DeleterEE" title="fmt::ptr::Deleter">Deleter</a>> &<em>p</em><span class="sig-paren">)</span> -> <em class="property">const</em> void*<a class="headerlink" href="#_CPPv4I00EN3fmt3ptrEPKvRKNSt10unique_ptrI1T7DeleterEE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt3ptrEPKvRKNSt10shared_ptrI1TEE"> <span id="_CPPv3I0EN3fmt3ptrERKNSt10shared_ptrI1TEE"></span><span id="_CPPv2I0EN3fmt3ptrERKNSt10shared_ptrI1TEE"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1ac0a9165f6676ea8fce0c34e7297e53a9"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">ptr</code><span class="sig-paren">(</span><em class="property">const</em> std::shared_ptr<<a class="reference internal" href="#_CPPv4I0EN3fmt3ptrEPKvRKNSt10shared_ptrI1TEE" title="fmt::ptr::T">T</a>> &<em>p</em><span class="sig-paren">)</span> -> <em class="property">const</em> void*<a class="headerlink" href="#_CPPv4I0EN3fmt3ptrEPKvRKNSt10shared_ptrI1TEE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt10underlyingE12underlying_tI4EnumE4Enum"> <span id="_CPPv3I0EN3fmt10underlyingE4Enum"></span><span id="_CPPv2I0EN3fmt10underlyingE4Enum"></span>template<typename <code class="sig-name descname">Enum</code>><br /><span class="target" id="format_8h_1a809639c35a5a0daa5e1cc84c522c75c9"></span><em class="property">constexpr</em> auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">underlying</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0EN3fmt10underlyingE12underlying_tI4EnumE4Enum" title="fmt::underlying::Enum">Enum</a> <em>e</em><span class="sig-paren">)</span> <em class="property">noexcept</em> -> underlying_t<<a class="reference internal" href="#_CPPv4I0EN3fmt10underlyingE12underlying_tI4EnumE4Enum" title="fmt::underlying::Enum">Enum</a>><a class="headerlink" href="#_CPPv4I0EN3fmt10underlyingE12underlying_tI4EnumE4Enum" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Converts <code class="docutils literal notranslate"><span class="pre">e</span></code> to the underlying type.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">color</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">red</span><span class="p">,</span><span class="w"> </span><span class="n">green</span><span class="p">,</span><span class="w"> </span><span class="n">blue</span><span class="w"> </span><span class="p">};</span> <span class="k">auto</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">underlying</span><span class="p">(</span><span class="n">color</span><span class="o">::</span><span class="n">red</span><span class="p">));</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt9to_stringENSt6stringERK1T"> <span id="_CPPv3I0EN3fmt9to_stringERK1T"></span><span id="_CPPv2I0EN3fmt9to_stringERK1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1ae498a7e951bb8f06f53bd6cb4e371633"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">to_string</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt9to_stringENSt6stringERK1T" title="fmt::to_string::T">T</a> &<em>value</em><span class="sig-paren">)</span> -> std::string<a class="headerlink" href="#_CPPv4I0EN3fmt9to_stringENSt6stringERK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Converts <em>value</em> to <code class="docutils literal notranslate"><span class="pre">std::string</span></code> using the default format for type <em>T</em>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/format.h></span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">answer</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">to_string</span><span class="p">(</span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view"> <span id="_CPPv3I0EN3fmt4joinERR5Range11string_view"></span><span id="_CPPv2I0EN3fmt4joinERR5Range11string_view"></span>template<typename <code class="sig-name descname">Range</code>><br /><span class="target" id="format_8h_1a4f98d49e3396fd35aba376cb0f40a882"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">join</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="fmt::join::Range">Range</a> &&<em>range</em>, <a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>sep</em><span class="sig-paren">)</span> -> join_view<detail::iterator_t<<a class="reference internal" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="fmt::join::Range">Range</a>>, detail::sentinel_t<<a class="reference internal" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="fmt::join::Range">Range</a>>><a class="headerlink" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Returns a view that formats <a class="reference internal" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="fmt::join::range"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">range</span></code></a> with elements separated by <a class="reference internal" href="#_CPPv4I0EN3fmt4joinE9join_viewIN6detail10iterator_tI5RangeEEN6detail10sentinel_tI5RangeEEERR5Range11string_view" title="fmt::join::sep"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">sep</span></code></a>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="kt">int</span><span class="o">></span><span class="w"> </span><span class="n">v</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">};</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">join</span><span class="p">(</span><span class="n">v</span><span class="p">,</span><span class="w"> </span><span class="s">", "</span><span class="p">));</span> <span class="c1">// Output: "1, 2, 3"</span> </pre></div> </div> <p><code class="docutils literal notranslate"><span class="pre">fmt::join</span></code> applies passed format specifiers to the range elements:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{:02}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">join</span><span class="p">(</span><span class="n">v</span><span class="p">,</span><span class="w"> </span><span class="s">", "</span><span class="p">));</span> <span class="c1">// Output: "01, 02, 03"</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view"> <span id="_CPPv3I00EN3fmt4joinE2It8Sentinel11string_view"></span><span id="_CPPv2I00EN3fmt4joinE2It8Sentinel11string_view"></span>template<typename <code class="sig-name descname">It</code>, typename <code class="sig-name descname">Sentinel</code>><br /><span class="target" id="format_8h_1a0d920c12aba189c116ca1a33aee29f7f"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">join</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view" title="fmt::join::It">It</a> <em>begin</em>, <a class="reference internal" href="#_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view" title="fmt::join::Sentinel">Sentinel</a> <em>end</em>, <a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>sep</em><span class="sig-paren">)</span> -> join_view<<a class="reference internal" href="#_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view" title="fmt::join::It">It</a>, <a class="reference internal" href="#_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view" title="fmt::join::Sentinel">Sentinel</a>><a class="headerlink" href="#_CPPv4I00EN3fmt4joinE9join_viewI2It8SentinelE2It8Sentinel11string_view" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns a view that formats the iterator range <code class="docutils literal notranslate"><span class="pre">[begin,</span> <span class="pre">end)</span></code> with elements separated by <code class="docutils literal notranslate"><span class="pre">sep</span></code>. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt12group_digitsE17group_digits_viewI1TE1T"> <span id="_CPPv3I0EN3fmt12group_digitsE1T"></span><span id="_CPPv2I0EN3fmt12group_digitsE1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1a229cf9b3f39965821d68af045a5f6cc4"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">group_digits</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0EN3fmt12group_digitsE17group_digits_viewI1TE1T" title="fmt::group_digits::T">T</a> <em>value</em><span class="sig-paren">)</span> -> group_digits_view<<a class="reference internal" href="#_CPPv4I0EN3fmt12group_digitsE17group_digits_viewI1TE1T" title="fmt::group_digits::T">T</a>><a class="headerlink" href="#_CPPv4I0EN3fmt12group_digitsE17group_digits_viewI1TE1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Returns a view that formats an integer value using ‘,’ as a locale-independent thousands separator.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">group_digits</span><span class="p">(</span><span class="mi">12345</span><span class="p">));</span> <span class="c1">// Output: "12,345"</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0EN3fmt6detail6bufferE"> <span id="_CPPv3I0EN3fmt6detail6bufferE"></span><span id="_CPPv2I0EN3fmt6detail6bufferE"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1detail_1_1buffer"></span><em class="property">class </em><code class="sig-prename descclassname">fmt::detail<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">buffer</code><a class="headerlink" href="#_CPPv4I0EN3fmt6detail6bufferE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>A contiguous memory buffer with an optional growing ability. It is an internal class and shouldn’t be used directly, only via <a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">basic_memory_buffer</span></code></a>.</p> </p> </p> <p>Subclassed by <a class="reference internal" href="#classfmt_1_1basic__memory__buffer"><span class="std std-ref">fmt::basic_memory_buffer< bigit, bigits_capacity ></span></a>, <a class="reference internal" href="#classfmt_1_1basic__memory__buffer"><span class="std std-ref">fmt::basic_memory_buffer< wchar_t ></span></a>, <a class="reference internal" href="#classfmt_1_1basic__memory__buffer"><span class="std std-ref">fmt::basic_memory_buffer< T, SIZE, Allocator ></span></a>, fmt::detail::counting_buffer< T >, fmt::detail::iterator_buffer< OutputIt, T, Traits >, fmt::detail::iterator_buffer< T *, T >, fmt::detail::iterator_buffer< T *, T, fixed_buffer_traits ></p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4NK3fmt6detail6buffer4sizeEv"> <span id="_CPPv3NK3fmt6detail6buffer4sizeEv"></span><span id="_CPPv2NK3fmt6detail6buffer4sizeEv"></span><span id="fmt::detail::buffer::sizeCCE"></span><span class="target" id="classfmt_1_1detail_1_1buffer_1a490109c8af99a7bbc522bab73c6d6a3f"></span><em class="property">constexpr</em> auto <code class="sig-name descname">size</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> size_t<a class="headerlink" href="#_CPPv4NK3fmt6detail6buffer4sizeEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns the size of this buffer. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4NK3fmt6detail6buffer8capacityEv"> <span id="_CPPv3NK3fmt6detail6buffer8capacityEv"></span><span id="_CPPv2NK3fmt6detail6buffer8capacityEv"></span><span id="fmt::detail::buffer::capacityCCE"></span><span class="target" id="classfmt_1_1detail_1_1buffer_1af35c750f68db5aee87528c56ad773fc3"></span><em class="property">constexpr</em> auto <code class="sig-name descname">capacity</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">const</em> <em class="property">noexcept</em> -> size_t<a class="headerlink" href="#_CPPv4NK3fmt6detail6buffer8capacityEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns the capacity of this buffer. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt6detail6buffer4dataEv"> <span id="_CPPv3N3fmt6detail6buffer4dataEv"></span><span id="_CPPv2N3fmt6detail6buffer4dataEv"></span><span id="fmt::detail::buffer::data"></span><span class="target" id="classfmt_1_1detail_1_1buffer_1ad520da92b9f427d5a1943c0806f55d99"></span>auto <code class="sig-name descname">data</code><span class="sig-paren">(</span><span class="sig-paren">)</span> <em class="property">noexcept</em> -> <a class="reference internal" href="#_CPPv4I0EN3fmt6detail6bufferE" title="fmt::detail::buffer::T">T</a>*<a class="headerlink" href="#_CPPv4N3fmt6detail6buffer4dataEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Returns a pointer to the buffer data (not null-terminated). </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt6detail6buffer5clearEv"> <span id="_CPPv3N3fmt6detail6buffer5clearEv"></span><span id="_CPPv2N3fmt6detail6buffer5clearEv"></span><span id="fmt::detail::buffer::clear"></span><span class="target" id="classfmt_1_1detail_1_1buffer_1ac64497e345116bae746b638cedb7ac20"></span>void <code class="sig-name descname">clear</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt6detail6buffer5clearEv" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Clears this buffer. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt6detail6buffer6appendEvPK1UPK1U"> <span id="_CPPv3I0EN3fmt6detail6buffer6appendEPK1UPK1U"></span><span id="_CPPv2I0EN3fmt6detail6buffer6appendEPK1UPK1U"></span>template<typename <code class="sig-name descname">U</code>><br /><span class="target" id="classfmt_1_1detail_1_1buffer_1afae920b7b90cc657d4bd9df9ceac4c2b"></span>void <code class="sig-name descname">append</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt6detail6buffer6appendEvPK1UPK1U" title="fmt::detail::buffer::append::U">U</a> *<em>begin</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt6detail6buffer6appendEvPK1UPK1U" title="fmt::detail::buffer::append::U">U</a> *<em>end</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I0EN3fmt6detail6buffer6appendEvPK1UPK1U" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Appends data to the end of the buffer. </p> </dd></dl> </div> </dd></dl> <dl class="cpp class"> <dt id="_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE"> <span id="_CPPv3I0_6size_t0EN3fmt19basic_memory_bufferE"></span><span id="_CPPv2I0_6size_t0EN3fmt19basic_memory_bufferE"></span>template<typename <code class="sig-name descname">T</code>, size_t <code class="sig-name descname">SIZE</code> = inline_buffer_size, typename <code class="sig-name descname">Allocator</code> = std::allocator<<a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer::T">T</a>>><br /><span class="target" id="classfmt_1_1basic__memory__buffer"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">basic_memory_buffer</code> : <em class="property">public</em> fmt::detail::<a class="reference internal" href="#_CPPv4I0EN3fmt6detail6bufferE" title="fmt::detail::buffer">buffer</a><<a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer::T">T</a>><a class="headerlink" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>A dynamically growing memory buffer for trivially copyable/constructible types with the first <code class="docutils literal notranslate"><span class="pre">SIZE</span></code> elements stored in the object itself.</p> <p>You can use the <code class="docutils literal notranslate"><span class="pre">memory_buffer</span></code> type alias for <code class="docutils literal notranslate"><span class="pre">char</span></code> instead.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span><span class="w"> </span><span class="n">out</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">memory_buffer</span><span class="p">();</span> <span class="n">fmt</span><span class="o">::</span><span class="n">format_to</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">back_inserter</span><span class="p">(</span><span class="n">out</span><span class="p">),</span><span class="w"> </span><span class="s">"The answer is {}."</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> <p>This will append the following output to the <code class="docutils literal notranslate"><span class="pre">out</span></code> object:</p> <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>The answer is 42. </pre></div> </div> <p>The output can be converted to an <code class="docutils literal notranslate"><span class="pre">std::string</span></code> with <code class="docutils literal notranslate"><span class="pre">to_string(out)</span></code>.</p> </p> </p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4N3fmt19basic_memory_buffer19basic_memory_bufferERR19basic_memory_buffer"> <span id="_CPPv3N3fmt19basic_memory_buffer19basic_memory_bufferERR19basic_memory_buffer"></span><span id="_CPPv2N3fmt19basic_memory_buffer19basic_memory_bufferERR19basic_memory_buffer"></span><span id="fmt::basic_memory_buffer::basic_memory_buffer__basic_memory_bufferRR"></span><span class="target" id="classfmt_1_1basic__memory__buffer_1aec38f6a7ca917da114e568bc15bc80f6"></span><code class="sig-name descname">basic_memory_buffer</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4N3fmt19basic_memory_buffer19basic_memory_bufferERR19basic_memory_buffer" title="fmt::basic_memory_buffer::basic_memory_buffer">basic_memory_buffer</a> &&<em>other</em><span class="sig-paren">)</span> <em class="property">noexcept</em><a class="headerlink" href="#_CPPv4N3fmt19basic_memory_buffer19basic_memory_bufferERR19basic_memory_buffer" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">fmt::basic_memory_buffer</span></code></a> object moving the content of the other object to it.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt19basic_memory_bufferaSERR19basic_memory_buffer"> <span id="_CPPv3N3fmt19basic_memory_bufferaSERR19basic_memory_buffer"></span><span id="_CPPv2N3fmt19basic_memory_bufferaSERR19basic_memory_buffer"></span><span id="fmt::basic_memory_buffer::assign-operator__basic_memory_bufferRR"></span><span class="target" id="classfmt_1_1basic__memory__buffer_1a4aba406807261c3f67426706f788bc83"></span>auto <code class="sig-name descname">operator=</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer">basic_memory_buffer</a> &&<em>other</em><span class="sig-paren">)</span> <em class="property">noexcept</em> -> <a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer">basic_memory_buffer</a>&<a class="headerlink" href="#_CPPv4N3fmt19basic_memory_bufferaSERR19basic_memory_buffer" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Moves the content of the other <code class="docutils literal notranslate"><span class="pre">basic_memory_buffer</span></code> object to this one.</p> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt19basic_memory_buffer6resizeE6size_t"> <span id="_CPPv3N3fmt19basic_memory_buffer6resizeE6size_t"></span><span id="_CPPv2N3fmt19basic_memory_buffer6resizeE6size_t"></span><span id="fmt::basic_memory_buffer::resize__s"></span><span class="target" id="classfmt_1_1basic__memory__buffer_1a29692fe33fa3b6a0a6af43e2368b80be"></span>void <code class="sig-name descname">resize</code><span class="sig-paren">(</span>size_t <em>count</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt19basic_memory_buffer6resizeE6size_t" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Resizes the buffer to contain <em>count</em> elements. </p> <p>If T is a POD type new elements may not be initialized. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt19basic_memory_buffer7reserveE6size_t"> <span id="_CPPv3N3fmt19basic_memory_buffer7reserveE6size_t"></span><span id="_CPPv2N3fmt19basic_memory_buffer7reserveE6size_t"></span><span id="fmt::basic_memory_buffer::reserve__s"></span><span class="target" id="classfmt_1_1basic__memory__buffer_1a8398ff2d3ab710d960b32d5695680551"></span>void <code class="sig-name descname">reserve</code><span class="sig-paren">(</span>size_t <em>new_capacity</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4N3fmt19basic_memory_buffer7reserveE6size_t" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Increases the buffer capacity to <em>new_capacity</em>. </p> </dd></dl> </div> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Protected Functions</p> <dl class="cpp function"> <dt id="_CPPv4N3fmt19basic_memory_buffer4growE6size_t"> <span id="_CPPv3N3fmt19basic_memory_buffer4growE6size_t"></span><span id="_CPPv2N3fmt19basic_memory_buffer4growE6size_t"></span><span id="fmt::basic_memory_buffer::grow__s"></span><span class="target" id="classfmt_1_1basic__memory__buffer_1aeca96953f3c076256cf069c6b0dfef07"></span>void <code class="sig-name descname">grow</code><span class="sig-paren">(</span>size_t <em>size</em><span class="sig-paren">)</span> <em class="property">override</em><a class="headerlink" href="#_CPPv4N3fmt19basic_memory_buffer4growE6size_t" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Increases the buffer capacity to hold at least <em>capacity</em> elements. </p> </dd></dl> </div> </dd></dl> </section> <section id="system-errors"> <h3>System Errors<a class="headerlink" href="#system-errors" title="Permalink to this headline">¶</a></h3> <p>{fmt} does not use <code class="docutils literal notranslate"><span class="pre">errno</span></code> to communicate errors to the user, but it may call system functions which set <code class="docutils literal notranslate"><span class="pre">errno</span></code>. Users should not make any assumptions about the value of <code class="docutils literal notranslate"><span class="pre">errno</span></code> being preserved by library functions.</p> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt12system_errorENSt12system_errorEi13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt12system_errorEi13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt12system_errorEi13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1aa2da9f32c148ea5b56bd8e744a428d28"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt12system_errorENSt12system_errorEi13format_stringIDp1TEDpRR1T" title="fmt::system_error::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">system_error</code><span class="sig-paren">(</span>int <em>error_code</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt12system_errorENSt12system_errorEi13format_stringIDp1TEDpRR1T" title="fmt::system_error::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt12system_errorENSt12system_errorEi13format_stringIDp1TEDpRR1T" title="fmt::system_error::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> std::system_error<a class="headerlink" href="#_CPPv4IDpEN3fmt12system_errorENSt12system_errorEi13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs <code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">std::system_error</span></code> with a message formatted with <code class="docutils literal notranslate"><span class="pre">fmt::format(fmt,</span> <span class="pre">args...)</span></code>. <em>error_code</em> is a system error code as given by <code class="docutils literal notranslate"><span class="pre">errno</span></code>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// This throws std::system_error with the description</span> <span class="c1">// cannot open file 'madeup': No such file or directory</span> <span class="c1">// or similar (system message may vary).</span> <span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">filename</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"madeup"</span><span class="p">;</span> <span class="n">std</span><span class="o">::</span><span class="kt">FILE</span><span class="o">*</span><span class="w"> </span><span class="n">file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">fopen</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span><span class="w"> </span><span class="s">"r"</span><span class="p">);</span> <span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">file</span><span class="p">)</span> <span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">system_error</span><span class="p">(</span><span class="n">errno</span><span class="p">,</span><span class="w"> </span><span class="s">"cannot open file '{}'"</span><span class="p">,</span><span class="w"> </span><span class="n">filename</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt19format_system_errorERN6detail6bufferIcEEiPKc"> <span id="_CPPv3N3fmt19format_system_errorERN6detail6bufferIcEEiPKc"></span><span id="_CPPv2N3fmt19format_system_errorERN6detail6bufferIcEEiPKc"></span><span id="fmt::format_system_error__detail::buffer:c:R.i.cCP"></span><span class="target" id="format_8h_1a51bce415ec78dfa92c6acecb16a69640"></span>void <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_system_error</code><span class="sig-paren">(</span>detail::<a class="reference internal" href="#_CPPv4I0EN3fmt6detail6bufferE" title="fmt::detail::buffer">buffer</a><char> &<em>out</em>, int <em>error_code</em>, <em class="property">const</em> char *<em>message</em><span class="sig-paren">)</span> <em class="property">noexcept</em><a class="headerlink" href="#_CPPv4N3fmt19format_system_errorERN6detail6bufferIcEEiPKc" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats an error message for an error returned by an operating system or a language runtime, for example a file opening error, and writes it to <em>out</em>. The format is the same as the one used by <code class="docutils literal notranslate"><span class="pre">std::system_error(ec,</span> <span class="pre">message)</span></code> where <code class="docutils literal notranslate"><span class="pre">ec</span></code> is <code class="docutils literal notranslate"><span class="pre">std::error_code(error_code,</span> <span class="pre">std::generic_category()})</span></code>. It is implementation-defined but normally looks like:</p> <pre class="literal-block"><em><message></em>: <em><system-message></em></pre> <p>where <em><message></em> is the passed message and <em><system-message></em> is the system message corresponding to the error code. <em>error_code</em> is a system error code as given by <code class="docutils literal notranslate"><span class="pre">errno</span></code>.</p> </p> </p> </dd></dl> </section> <section id="custom-allocators"> <h3>Custom Allocators<a class="headerlink" href="#custom-allocators" title="Permalink to this headline">¶</a></h3> <p>The {fmt} library supports custom dynamic memory allocators. A custom allocator class can be specified as a template argument to <a class="reference internal" href="#_CPPv4I0_6size_t0EN3fmt19basic_memory_bufferE" title="fmt::basic_memory_buffer"><code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">fmt::basic_memory_buffer</span></code></a>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">using</span><span class="w"> </span><span class="n">custom_memory_buffer</span><span class="w"> </span><span class="o">=</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">basic_memory_buffer</span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">inline_buffer_size</span><span class="p">,</span><span class="w"> </span><span class="n">custom_allocator</span><span class="o">></span><span class="p">;</span> </pre></div> </div> <p>It is also possible to write a formatting function that uses a custom allocator:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">using</span><span class="w"> </span><span class="n">custom_string</span><span class="w"> </span><span class="o">=</span> <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">basic_string</span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">char_traits</span><span class="o"><</span><span class="kt">char</span><span class="o">></span><span class="p">,</span><span class="w"> </span><span class="n">custom_allocator</span><span class="o">></span><span class="p">;</span> <span class="n">custom_string</span><span class="w"> </span><span class="nf">vformat</span><span class="p">(</span><span class="n">custom_allocator</span><span class="w"> </span><span class="n">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">string_view</span><span class="w"> </span><span class="n">format_str</span><span class="p">,</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format_args</span><span class="w"> </span><span class="n">args</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">buf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">custom_memory_buffer</span><span class="p">(</span><span class="n">alloc</span><span class="p">);</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">vformat_to</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">back_inserter</span><span class="p">(</span><span class="n">buf</span><span class="p">),</span><span class="w"> </span><span class="n">format_str</span><span class="p">,</span><span class="w"> </span><span class="n">args</span><span class="p">);</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">custom_string</span><span class="p">(</span><span class="n">buf</span><span class="p">.</span><span class="n">data</span><span class="p">(),</span><span class="w"> </span><span class="n">buf</span><span class="p">.</span><span class="n">size</span><span class="p">(),</span><span class="w"> </span><span class="n">alloc</span><span class="p">);</span> <span class="p">}</span> <span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">typename</span><span class="w"> </span><span class="p">...</span><span class="n">Args</span><span class="o">></span> <span class="kr">inline</span><span class="w"> </span><span class="n">custom_string</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="n">custom_allocator</span><span class="w"> </span><span class="n">alloc</span><span class="p">,</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">string_view</span><span class="w"> </span><span class="n">format_str</span><span class="p">,</span> <span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">Args</span><span class="o">&</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="n">args</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">vformat</span><span class="p">(</span><span class="n">alloc</span><span class="p">,</span><span class="w"> </span><span class="n">format_str</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">make_format_args</span><span class="p">(</span><span class="n">args</span><span class="p">...));</span> <span class="p">}</span> </pre></div> </div> <p>The allocator will be used for the output container only. Formatting functions normally don’t do any allocations for built-in and string types except for non-default floating-point formatting that occasionally falls back on <code class="docutils literal notranslate"><span class="pre">sprintf</span></code>.</p> </section> <section id="locale"> <h3>Locale<a class="headerlink" href="#locale" title="Permalink to this headline">¶</a></h3> <p>All formatting is locale-independent by default. Use the <code class="docutils literal notranslate"><span class="pre">'L'</span></code> format specifier to insert the appropriate number separator characters from the locale:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/core.h></span> <span class="cp">#include</span><span class="w"> </span><span class="cpf"><locale></span> <span class="n">std</span><span class="o">::</span><span class="n">locale</span><span class="o">::</span><span class="n">global</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">locale</span><span class="p">(</span><span class="s">"en_US.UTF-8"</span><span class="p">));</span> <span class="k">auto</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"{:L}"</span><span class="p">,</span><span class="w"> </span><span class="mi">1000000</span><span class="p">);</span><span class="w"> </span><span class="c1">// s == "1,000,000"</span> </pre></div> </div> <p><code class="docutils literal notranslate"><span class="pre">fmt/format.h</span></code> provides the following overloads of formatting functions that take <code class="docutils literal notranslate"><span class="pre">std::locale</span></code> as a parameter. The locale type is a template parameter to avoid the expensive <code class="docutils literal notranslate"><span class="pre"><locale></span></code> include.</p> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T"> <span id="_CPPv3I0DpEN3fmt6formatERK6Locale13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2I0DpEN3fmt6formatERK6Locale13format_stringIDp1TEDpRR1T"></span>template<typename <code class="sig-name descname">Locale</code>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1ab14dd1acbc55791fb7c9c072a7280348"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format::Locale">Locale</a> &<em>loc</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> std::string<a class="headerlink" href="#_CPPv4I0DpEN3fmt6formatENSt6stringERK6Locale13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T"> <span id="_CPPv3I00DpEN3fmt9format_toE8OutputItRK6Locale13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2I00DpEN3fmt9format_toE8OutputItRK6Locale13format_stringIDp1TEDpRR1T"></span>template<typename <code class="sig-name descname">OutputIt</code>, typename <code class="sig-name descname">Locale</code>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1a789034b65987d8a507e00538cab50d7a"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">format_to</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::OutputIt">OutputIt</a> <em>out</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::Locale">Locale</a> &<em>loc</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> <a class="reference internal" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::format_to::OutputIt">OutputIt</a><a class="headerlink" href="#_CPPv4I00DpEN3fmt9format_toE8OutputIt8OutputItRK6Locale13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T"> <span id="_CPPv3I0DpEN3fmt14formatted_sizeERK6Locale13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2I0DpEN3fmt14formatted_sizeERK6Locale13format_stringIDp1TEDpRR1T"></span>template<typename <code class="sig-name descname">Locale</code>, typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="format_8h_1a736542f7b3651a668bc113a74e28f1c6"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">formatted_size</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::Locale">Locale</a> &<em>loc</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T" title="fmt::formatted_size::T">T</a>&&... <em>args</em><span class="sig-paren">)</span> -> size_t<a class="headerlink" href="#_CPPv4I0DpEN3fmt14formatted_sizeE6size_tRK6Locale13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> </section> <section id="legacy-compile-time-format-string-checks"> <span id="legacy-checks"></span><h3>Legacy Compile-Time Format String Checks<a class="headerlink" href="#legacy-compile-time-format-string-checks" title="Permalink to this headline">¶</a></h3> <p><code class="docutils literal notranslate"><span class="pre">FMT_STRING</span></code> enables compile-time checks on older compilers. It requires C++14 or later and is a no-op in C++11.</p> <dl class="cpp macro"> <dt id="c.FMT_STRING"> <span class="target" id="format_8h_1a09119ad072f708d17b88704fa898aff0"></span><code class="sig-name descname">FMT_STRING</code><span class="sig-paren">(</span><em>s</em><span class="sig-paren">)</span><a class="headerlink" href="#c.FMT_STRING" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a compile-time format string from a string literal <em>s</em>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// A compile-time error because 'd' is an invalid specifier for strings.</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="n">FMT_STRING</span><span class="p">(</span><span class="s">"{:d}"</span><span class="p">),</span><span class="w"> </span><span class="s">"foo"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <p>To force the use of legacy compile-time checks, define the preprocessor variable <code class="docutils literal notranslate"><span class="pre">FMT_ENFORCE_COMPILE_STRING</span></code>. When set, functions accepting <code class="docutils literal notranslate"><span class="pre">FMT_STRING</span></code> will fail to compile with regular strings.</p> </section> </section> <section id="range-and-tuple-formatting"> <span id="ranges-api"></span><h2>Range and Tuple Formatting<a class="headerlink" href="#range-and-tuple-formatting" title="Permalink to this headline">¶</a></h2> <p>The library also supports convenient formatting of ranges and tuples:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/ranges.h></span> <span class="n">std</span><span class="o">::</span><span class="n">tuple</span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="kt">float</span><span class="o">></span><span class="w"> </span><span class="n">t</span><span class="p">{</span><span class="sc">'a'</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mf">2.0f</span><span class="p">};</span> <span class="c1">// Prints "('a', 1, 2.0)"</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">t</span><span class="p">);</span> </pre></div> </div> <p>NOTE: currently, the overload of <code class="docutils literal notranslate"><span class="pre">fmt::join</span></code> for iterables exists in the main <code class="docutils literal notranslate"><span class="pre">format.h</span></code> header, but expect this to change in the future.</p> <p>Using <code class="docutils literal notranslate"><span class="pre">fmt::join</span></code>, you can separate tuple elements with a custom separator:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/ranges.h></span> <span class="n">std</span><span class="o">::</span><span class="n">tuple</span><span class="o"><</span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="kt">char</span><span class="o">></span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">{</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="sc">'a'</span><span class="p">};</span> <span class="c1">// Prints "1, a"</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">join</span><span class="p">(</span><span class="n">t</span><span class="p">,</span><span class="w"> </span><span class="s">", "</span><span class="p">));</span> </pre></div> </div> </section> <section id="date-and-time-formatting"> <span id="chrono-api"></span><h2>Date and Time Formatting<a class="headerlink" href="#date-and-time-formatting" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/chrono.h</span></code> provides formatters for</p> <ul class="simple"> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/chrono/duration">std::chrono::duration</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/chrono/time_point">std::chrono::time_point</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/chrono/c/tm">std::tm</a></p></li> </ul> <p>The format syntax is described in <a class="reference internal" href="syntax.html#chrono-specs"><span class="std std-ref">Chrono Format Specifications</span></a>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/chrono.h></span> <span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="kt">time_t</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">time</span><span class="p">(</span><span class="k">nullptr</span><span class="p">);</span> <span class="w"> </span><span class="c1">// Prints "The date is 2020-11-07." (with the current date):</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"The date is {:%Y-%m-%d}."</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">localtime</span><span class="p">(</span><span class="n">t</span><span class="p">));</span> <span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="k">namespace</span><span class="w"> </span><span class="nn">std</span><span class="o">::</span><span class="nn">literals</span><span class="o">::</span><span class="nn">chrono_literals</span><span class="p">;</span> <span class="w"> </span><span class="c1">// Prints "Default format: 42s 100ms":</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Default format: {} {}</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="n">s</span><span class="p">,</span><span class="w"> </span><span class="mi">100</span><span class="n">ms</span><span class="p">);</span> <span class="w"> </span><span class="c1">// Prints "strftime-like format: 03:15:30":</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"strftime-like format: {:%H:%M:%S}</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="n">h</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">15</span><span class="n">min</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">30</span><span class="n">s</span><span class="p">);</span> <span class="p">}</span> </pre></div> </div> <dl class="cpp function"> <dt id="_CPPv4N3fmt9localtimeENSt6time_tE"> <span id="_CPPv3N3fmt9localtimeENSt6time_tE"></span><span id="_CPPv2N3fmt9localtimeENSt6time_tE"></span><span id="fmt::localtime__std::time_t"></span><span class="target" id="chrono_8h_1a643b7f36289ce0547f217d387f47bbf3"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">localtime</code><span class="sig-paren">(</span>std::time_t <em>time</em><span class="sig-paren">)</span> -> std::tm<a class="headerlink" href="#_CPPv4N3fmt9localtimeENSt6time_tE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Converts given time since epoch as <code class="docutils literal notranslate"><span class="pre">std::time_t</span></code> value into calendar time, expressed in local time. </p> <p>Unlike <code class="docutils literal notranslate"><span class="pre">std::localtime</span></code>, this function is thread-safe on most platforms. </p> </dd></dl> <div class="admonition warning"> <p class="admonition-title">Warning</p> <p>doxygenfunction: Unable to resolve multiple matches for function “gmtime” with arguments ((std::time_t)) in doxygen xml output for project “format” from directory: /Users/viz/work/fmt/support/build/fmt/doc/doxyxml. Potential matches: </p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="o">-</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">gmtime</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="kt">time_t</span><span class="w"> </span><span class="n">time</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">tm</span> <span class="o">-</span><span class="w"> </span><span class="k">template</span><span class="o"><</span><span class="k">typename</span><span class="w"> </span><span class="nc">Duration</span><span class="o">></span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">gmtime</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">chrono</span><span class="o">::</span><span class="n">time_point</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">chrono</span><span class="o">::</span><span class="n">system_clock</span><span class="p">,</span><span class="w"> </span><span class="n">Duration</span><span class="o">></span><span class="w"> </span><span class="n">time_point</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">tm</span> </pre></div> </div> </div> </section> <section id="standard-library-types-formatting"> <span id="std-api"></span><h2>Standard Library Types Formatting<a class="headerlink" href="#standard-library-types-formatting" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/std.h</span></code> provides formatters for:</p> <ul class="simple"> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/filesystem/path">std::filesystem::path</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/thread/thread/id">std::thread::id</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/utility/variant/monostate">std::monostate</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/utility/variant/variant">std::variant</a></p></li> <li><p><a class="reference external" href="https://en.cppreference.com/w/cpp/utility/optional">std::optional</a></p></li> </ul> <section id="formatting-variants"> <h3>Formatting Variants<a class="headerlink" href="#formatting-variants" title="Permalink to this headline">¶</a></h3> <p>A <code class="docutils literal notranslate"><span class="pre">std::variant</span></code> is only formattable if every variant alternative is formattable, and requires the <code class="docutils literal notranslate"><span class="pre">__cpp_lib_variant</span></code> <a class="reference external" href="https://en.cppreference.com/w/cpp/feature_test">library feature</a>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/std.h></span> <span class="n">std</span><span class="o">::</span><span class="n">variant</span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="kt">float</span><span class="o">></span><span class="w"> </span><span class="n">v0</span><span class="p">{</span><span class="sc">'x'</span><span class="p">};</span> <span class="c1">// Prints "variant('x')"</span> <span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span><span class="w"> </span><span class="n">v0</span><span class="p">);</span> <span class="n">std</span><span class="o">::</span><span class="n">variant</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">monostate</span><span class="p">,</span><span class="w"> </span><span class="kt">char</span><span class="o">></span><span class="w"> </span><span class="n">v1</span><span class="p">;</span> <span class="c1">// Prints "variant(monostate)"</span> </pre></div> </div> </section> </section> <section id="format-string-compilation"> <span id="compile-api"></span><h2>Format String Compilation<a class="headerlink" href="#format-string-compilation" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/compile.h</span></code> provides format string compilation enabled via the <code class="docutils literal notranslate"><span class="pre">FMT_COMPILE</span></code> macro or the <code class="docutils literal notranslate"><span class="pre">_cf</span></code> user-defined literal. Format strings marked with <code class="docutils literal notranslate"><span class="pre">FMT_COMPILE</span></code> or <code class="docutils literal notranslate"><span class="pre">_cf</span></code> are parsed, checked and converted into efficient formatting code at compile-time. This supports arguments of built-in and string types as well as user-defined types with <code class="docutils literal notranslate"><span class="pre">format</span></code> functions taking the format context type as a template parameter in their <code class="docutils literal notranslate"><span class="pre">formatter</span></code> specializations. For example:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">template</span><span class="w"> </span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">point</span><span class="o">></span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">parse</span><span class="p">(</span><span class="n">format_parse_context</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">);</span> <span class="w"> </span><span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">typename</span><span class="w"> </span><span class="nc">FormatContext</span><span class="o">></span> <span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">format</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">point</span><span class="o">&</span><span class="w"> </span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="n">FormatContext</span><span class="o">&</span><span class="w"> </span><span class="n">ctx</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="p">;</span> <span class="p">};</span> </pre></div> </div> <p>Format string compilation can generate more binary code compared to the default API and is only recommended in places where formatting is a performance bottleneck.</p> <dl class="cpp macro"> <dt id="c.FMT_COMPILE"> <span class="target" id="compile_8h_1a7186ba53487a4df4602ae1d75658db29"></span><code class="sig-name descname">FMT_COMPILE</code><span class="sig-paren">(</span><em>s</em><span class="sig-paren">)</span><a class="headerlink" href="#c.FMT_COMPILE" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Converts a string literal <em>s</em> into a format string that will be parsed at compile time and converted into efficient formatting code. Requires C++17 <code class="docutils literal notranslate"><span class="pre">constexpr</span> <span class="pre">if</span></code> compiler support.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// Converts 42 into std::string using the most efficient method and no</span> <span class="c1">// runtime format string processing.</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="n">FMT_COMPILE</span><span class="p">(</span><span class="s">"{}"</span><span class="p">),</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I_N15detail_exported12fixed_stringEEN3fmtli3_cfEDav"> <span id="_CPPv3I_N15detail_exported12fixed_stringEEN3fmtli3_cfEv"></span><span id="_CPPv2I_N15detail_exported12fixed_stringEEN3fmtli3_cfEv"></span>template<detail_exported::fixed_string <code class="sig-name descname">Str</code>><br /><span class="target" id="compile_8h_1a79b71ea3d1d76cb384707cf16136fad5"></span><em class="property">constexpr</em> auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">operator""_cf</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I_N15detail_exported12fixed_stringEEN3fmtli3_cfEDav" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> </section> <section id="terminal-color-and-text-style"> <span id="color-api"></span><h2>Terminal Color and Text Style<a class="headerlink" href="#terminal-color-and-text-style" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/color.h</span></code> provides support for terminal color and text style output.</p> <dl class="cpp function"> <dt id="_CPPv4I0DpEN3fmt5printEvRK10text_styleRK1SDpRK4Args"> <span id="_CPPv3I0DpEN3fmt5printERK10text_styleRK1SDpRK4Args"></span><span id="_CPPv2I0DpEN3fmt5printERK10text_styleRK1SDpRK4Args"></span>template<typename <code class="sig-name descname">S</code>, typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="color_8h_1a2cc2ce51809b329a491730a7b7c13318"></span>void <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">print</code><span class="sig-paren">(</span><em class="property">const</em> text_style &<em>ts</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0DpEN3fmt5printEvRK10text_styleRK1SDpRK4Args" title="fmt::print::S">S</a> &<em>format_str</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0DpEN3fmt5printEvRK10text_styleRK1SDpRK4Args" title="fmt::print::Args">Args</a>&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4I0DpEN3fmt5printEvRK10text_styleRK1SDpRK4Args" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats a string and prints it to stdout using ANSI escape sequences to specify text formatting.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="n">fmt</span><span class="o">::</span><span class="n">emphasis</span><span class="o">::</span><span class="n">bold</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">fg</span><span class="p">(</span><span class="n">fmt</span><span class="o">::</span><span class="n">color</span><span class="o">::</span><span class="n">red</span><span class="p">),</span> <span class="w"> </span><span class="s">"Elapsed time: {0:.2f} seconds"</span><span class="p">,</span><span class="w"> </span><span class="mf">1.23</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt2fgEN6detail10color_typeE"> <span id="_CPPv3N3fmt2fgEN6detail10color_typeE"></span><span id="_CPPv2N3fmt2fgEN6detail10color_typeE"></span><span id="fmt::fg__detail::color_type"></span><span class="target" id="color_8h_1aa0997aeb59a9ecd0592c556d36359d8f"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">fg</code><span class="sig-paren">(</span>detail::color_type <em>foreground</em><span class="sig-paren">)</span> <em class="property">noexcept</em> -> text_style<a class="headerlink" href="#_CPPv4N3fmt2fgEN6detail10color_typeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Creates a text style from the foreground (text) color. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4N3fmt2bgEN6detail10color_typeE"> <span id="_CPPv3N3fmt2bgEN6detail10color_typeE"></span><span id="_CPPv2N3fmt2bgEN6detail10color_typeE"></span><span id="fmt::bg__detail::color_type"></span><span class="target" id="color_8h_1a0878ee99fc1b522a83a6bf983fafb25c"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">bg</code><span class="sig-paren">(</span>detail::color_type <em>background</em><span class="sig-paren">)</span> <em class="property">noexcept</em> -> text_style<a class="headerlink" href="#_CPPv4N3fmt2bgEN6detail10color_typeE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Creates a text style from the background color. </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt6styledEN6detail10styled_argI14remove_cvref_tI1TEEERK1T10text_style"> <span id="_CPPv3I0EN3fmt6styledERK1T10text_style"></span><span id="_CPPv2I0EN3fmt6styledERK1T10text_style"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="color_8h_1aaa994d7fe55bf7b40810e55b362fe107"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">styled</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt6styledEN6detail10styled_argI14remove_cvref_tI1TEEERK1T10text_style" title="fmt::styled::T">T</a> &<em>value</em>, text_style <em>ts</em><span class="sig-paren">)</span> -> detail::styled_arg<remove_cvref_t<<a class="reference internal" href="#_CPPv4I0EN3fmt6styledEN6detail10styled_argI14remove_cvref_tI1TEEERK1T10text_style" title="fmt::styled::T">T</a>>><a class="headerlink" href="#_CPPv4I0EN3fmt6styledEN6detail10styled_argI14remove_cvref_tI1TEEERK1T10text_style" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Returns an argument that will be formatted using ANSI escape sequences, to be used in a formatting function.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Elapsed time: {0:.2f} seconds"</span><span class="p">,</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">styled</span><span class="p">(</span><span class="mf">1.23</span><span class="p">,</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">fg</span><span class="p">(</span><span class="n">fmt</span><span class="o">::</span><span class="n">color</span><span class="o">::</span><span class="n">green</span><span class="p">)</span><span class="w"> </span><span class="o">|</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">bg</span><span class="p">(</span><span class="n">fmt</span><span class="o">::</span><span class="n">color</span><span class="o">::</span><span class="n">blue</span><span class="p">)));</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="system-apis"> <span id="os-api"></span><h2>System APIs<a class="headerlink" href="#system-apis" title="Permalink to this headline">¶</a></h2> <dl class="cpp class"> <dt id="_CPPv4N3fmt7ostreamE"> <span id="_CPPv3N3fmt7ostreamE"></span><span id="_CPPv2N3fmt7ostreamE"></span><span id="fmt::ostream"></span><span class="target" id="classfmt_1_1ostream"></span><em class="property">class </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">ostream</code><a class="headerlink" href="#_CPPv4N3fmt7ostreamE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>A fast output stream which is not thread-safe. </p> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Public Functions</p> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt7ostream5printEv13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt7ostream5printE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt7ostream5printE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1ostream_1aeffd7c3e05f5178e689dd18e648704d5"></span>void <code class="sig-name descname">print</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt7ostream5printEv13format_stringIDp1TEDpRR1T" title="fmt::ostream::print::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt7ostream5printEv13format_stringIDp1TEDpRR1T" title="fmt::ostream::print::T">T</a>&&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt7ostream5printEv13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Formats <code class="docutils literal notranslate"><span class="pre">args</span></code> according to specifications in <code class="docutils literal notranslate"><span class="pre">fmt</span></code> and writes the output to the file. </p> </dd></dl> </div> <div class="breathe-sectiondef docutils container"> <p class="breathe-sectiondef-title rubric">Friends</p> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt7ostream11output_fileE7ostream12cstring_viewDp1T"> <span id="_CPPv3IDpEN3fmt7ostream11output_fileE12cstring_viewDp1T"></span><span id="_CPPv2IDpEN3fmt7ostream11output_fileE12cstring_viewDp1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="classfmt_1_1ostream_1a3bac45a0a6f48bd4d040e023e4f89bbc"></span>auto <code class="sig-name descname">output_file</code><span class="sig-paren">(</span>cstring_view <em>path</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt7ostream11output_fileE7ostream12cstring_viewDp1T" title="fmt::ostream::output_file::T">T</a>... <em>params</em><span class="sig-paren">)</span> -> <a class="reference internal" href="#_CPPv4N3fmt7ostreamE" title="fmt::ostream">ostream</a><a class="headerlink" href="#_CPPv4IDpEN3fmt7ostream11output_fileE7ostream12cstring_viewDp1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Opens a file for writing. Supported parameters passed in <em>params</em>:</p> <ul class="simple"> <li><p><code class="docutils literal notranslate"><span class="pre"><integer></span></code>: Flags passed to <a class="reference external" href="https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html">open</a> (<code class="docutils literal notranslate"><span class="pre">file::WRONLY</span> <span class="pre">|</span> <span class="pre">file::CREATE</span> <span class="pre">|</span> <span class="pre">file::TRUNC</span></code> by default)</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">buffer_size=<integer></span></code>: Output buffer size</p></li> </ul> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span><span class="w"> </span><span class="n">out</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">output_file</span><span class="p">(</span><span class="s">"guide.txt"</span><span class="p">);</span> <span class="n">out</span><span class="p">.</span><span class="n">print</span><span class="p">(</span><span class="s">"Don't {}"</span><span class="p">,</span><span class="w"> </span><span class="s">"Panic"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> </div> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt13windows_errorENSt12system_errorEi11string_viewDpRK4Args"> <span id="_CPPv3IDpEN3fmt13windows_errorEi11string_viewDpRK4Args"></span><span id="_CPPv2IDpEN3fmt13windows_errorEi11string_viewDpRK4Args"></span>template<typename ...<code class="sig-name descname">Args</code>><br /><span class="target" id="os_8h_1a0bee0ab8ecd5254a4612f3c9145a03e2"></span>std::system_error <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">windows_error</code><span class="sig-paren">(</span>int <em>error_code</em>, <a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>message</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4IDpEN3fmt13windows_errorENSt12system_errorEi11string_viewDpRK4Args" title="fmt::windows_error::Args">Args</a>&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt13windows_errorENSt12system_errorEi11string_viewDpRK4Args" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Constructs a <code class="xref cpp cpp-class docutils literal notranslate"><span class="pre">std::system_error</span></code> object with the description of the form</p> <pre class="literal-block"><em><message></em>: <em><system-message></em></pre> <p>where <em><message></em> is the formatted message and <em><system-message></em> is the system message corresponding to the error code. <em>error_code</em> is a Windows error code as given by <code class="docutils literal notranslate"><span class="pre">GetLastError</span></code>. If <em>error_code</em> is not a valid error code such as -1, the system message will look like “error -1”.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">// This throws a system_error with the description</span> <span class="c1">// cannot open file 'madeup': The system cannot find the file specified.</span> <span class="c1">// or similar (system message may vary).</span> <span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="o">*</span><span class="n">filename</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"madeup"</span><span class="p">;</span> <span class="n">LPOFSTRUCT</span><span class="w"> </span><span class="n">of</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">LPOFSTRUCT</span><span class="p">();</span> <span class="n">HFILE</span><span class="w"> </span><span class="n">file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">OpenFile</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">of</span><span class="p">,</span><span class="w"> </span><span class="n">OF_READ</span><span class="p">);</span> <span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">file</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">HFILE_ERROR</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">windows_error</span><span class="p">(</span><span class="n">GetLastError</span><span class="p">(),</span> <span class="w"> </span><span class="s">"cannot open file '{}'"</span><span class="p">,</span><span class="w"> </span><span class="n">filename</span><span class="p">);</span> <span class="p">}</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="std-ostream-support"> <span id="ostream-api"></span><h2><code class="docutils literal notranslate"><span class="pre">std::ostream</span></code> Support<a class="headerlink" href="#std-ostream-support" title="Permalink to this headline">¶</a></h2> <p><code class="docutils literal notranslate"><span class="pre">fmt/ostream.h</span></code> provides <code class="docutils literal notranslate"><span class="pre">std::ostream</span></code> support including formatting of user-defined types that have an overloaded insertion operator (<code class="docutils literal notranslate"><span class="pre">operator<<</span></code>). In order to make a type formattable via <code class="docutils literal notranslate"><span class="pre">std::ostream</span></code> you should provide a <code class="docutils literal notranslate"><span class="pre">formatter</span></code> specialization inherited from <code class="docutils literal notranslate"><span class="pre">ostream_formatter</span></code>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><fmt/ostream.h></span> <span class="k">struct</span><span class="w"> </span><span class="nc">date</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">year</span><span class="p">,</span><span class="w"> </span><span class="n">month</span><span class="p">,</span><span class="w"> </span><span class="n">day</span><span class="p">;</span> <span class="w"> </span><span class="k">friend</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">ostream</span><span class="o">&</span><span class="w"> </span><span class="k">operator</span><span class="o"><<</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">ostream</span><span class="o">&</span><span class="w"> </span><span class="n">os</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">date</span><span class="o">&</span><span class="w"> </span><span class="n">d</span><span class="p">)</span><span class="w"> </span><span class="p">{</span> <span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">os</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">d</span><span class="p">.</span><span class="n">year</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="sc">'-'</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">d</span><span class="p">.</span><span class="n">month</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="sc">'-'</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">d</span><span class="p">.</span><span class="n">day</span><span class="p">;</span> <span class="w"> </span><span class="p">}</span> <span class="p">};</span> <span class="k">template</span><span class="w"> </span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">fmt</span><span class="o">::</span><span class="n">formatter</span><span class="o"><</span><span class="n">date</span><span class="o">></span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">ostream_formatter</span><span class="w"> </span><span class="p">{};</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(</span><span class="s">"The date is {}"</span><span class="p">,</span><span class="w"> </span><span class="n">date</span><span class="p">{</span><span class="mi">2012</span><span class="p">,</span><span class="w"> </span><span class="mi">12</span><span class="p">,</span><span class="w"> </span><span class="mi">9</span><span class="p">});</span> <span class="c1">// s == "The date is 2012-12-9"</span> </pre></div> </div> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt8streamedEN6detail13streamed_viewI1TEERK1T"> <span id="_CPPv3I0EN3fmt8streamedERK1T"></span><span id="_CPPv2I0EN3fmt8streamedERK1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="ostream_8h_1afc1c53e60beb681b5b03d94d906769f6"></span><em class="property">constexpr</em> auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">streamed</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt8streamedEN6detail13streamed_viewI1TEERK1T" title="fmt::streamed::T">T</a> &<em>value</em><span class="sig-paren">)</span> -> detail::streamed_view<<a class="reference internal" href="#_CPPv4I0EN3fmt8streamedEN6detail13streamed_viewI1TEERK1T" title="fmt::streamed::T">T</a>><a class="headerlink" href="#_CPPv4I0EN3fmt8streamedEN6detail13streamed_viewI1TEERK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Returns a view that formats <a class="reference internal" href="#_CPPv4I0EN3fmt8streamedEN6detail13streamed_viewI1TEERK1T" title="fmt::streamed::value"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">value</span></code></a> via an ostream <code class="docutils literal notranslate"><span class="pre">operator<<</span></code>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="s">"Current thread id: {}</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">streamed</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">this_thread</span><span class="o">::</span><span class="n">get_id</span><span class="p">()));</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt5printEvRNSt7ostreamE13format_stringIDp1TEDpRR1T"> <span id="_CPPv3IDpEN3fmt5printERNSt7ostreamE13format_stringIDp1TEDpRR1T"></span><span id="_CPPv2IDpEN3fmt5printERNSt7ostreamE13format_stringIDp1TEDpRR1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="ostream_8h_1a091104cf24873dda703cb3a3202f25f5"></span>void <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvRNSt7ostreamE13format_stringIDp1TEDpRR1T" title="fmt::print::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">print</code><span class="sig-paren">(</span>std::ostream &<em>os</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt13format_stringE" title="fmt::format_string">format_string</a><<a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvRNSt7ostreamE13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>...> <em>fmt</em>, <a class="reference internal" href="#_CPPv4IDpEN3fmt5printEvRNSt7ostreamE13format_stringIDp1TEDpRR1T" title="fmt::print::T">T</a>&&... <em>args</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv4IDpEN3fmt5printEvRNSt7ostreamE13format_stringIDp1TEDpRR1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Prints formatted data to the stream <em>os</em>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">print</span><span class="p">(</span><span class="n">cerr</span><span class="p">,</span><span class="w"> </span><span class="s">"Don't {}!"</span><span class="p">,</span><span class="w"> </span><span class="s">"panic"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="printf-formatting"> <span id="printf-api"></span><h2><code class="docutils literal notranslate"><span class="pre">printf</span></code> Formatting<a class="headerlink" href="#printf-formatting" title="Permalink to this headline">¶</a></h2> <p>The header <code class="docutils literal notranslate"><span class="pre">fmt/printf.h</span></code> provides <code class="docutils literal notranslate"><span class="pre">printf</span></code>-like formatting functionality. The following functions use <a class="reference external" href="https://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html">printf format string syntax</a> with the POSIX extension for positional arguments. Unlike their standard counterparts, the <code class="docutils literal notranslate"><span class="pre">fmt</span></code> functions are type-safe and throw an exception if an argument type doesn’t match its format specification.</p> <dl class="cpp function"> <dt id="_CPPv4IDpEN3fmt6printfEi11string_viewDpRK1T"> <span id="_CPPv3IDpEN3fmt6printfE11string_viewDpRK1T"></span><span id="_CPPv2IDpEN3fmt6printfE11string_viewDpRK1T"></span>template<typename ...<code class="sig-name descname">T</code>><br /><span class="target" id="printf_8h_1a40037d3bb325dbb41ffdefaa3063fc61"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4IDpEN3fmt6printfEi11string_viewDpRK1T" title="fmt::printf::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">printf</code><span class="sig-paren">(</span><a class="reference internal" href="#_CPPv4N3fmt11string_viewE" title="fmt::string_view">string_view</a> <em>fmt</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4IDpEN3fmt6printfEi11string_viewDpRK1T" title="fmt::printf::T">T</a>&... <em>args</em><span class="sig-paren">)</span> -> int<a class="headerlink" href="#_CPPv4IDpEN3fmt6printfEi11string_viewDpRK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Prints formatted data to <code class="docutils literal notranslate"><span class="pre">stdout</span></code>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">printf</span><span class="p">(</span><span class="s">"Elapsed time: %.2f seconds"</span><span class="p">,</span><span class="w"> </span><span class="mf">1.23</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T"> <span id="_CPPv3I0Dp0EN3fmt7fprintfEPNSt4FILEERK1SDpRK1T"></span><span id="_CPPv2I0Dp0EN3fmt7fprintfEPNSt4FILEERK1SDpRK1T"></span>template<typename <code class="sig-name descname">S</code>, typename ...<code class="sig-name descname">T</code>, typename <code class="sig-name descname">Char</code> = char_t<<a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T" title="fmt::fprintf::S">S</a>>><br /><span class="target" id="printf_8h_1a4f91e0cd05d87b5d3d3b77eee1a7d07a"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T" title="fmt::fprintf::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">fprintf</code><span class="sig-paren">(</span>std::FILE *<em>f</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T" title="fmt::fprintf::S">S</a> &<em>fmt</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T" title="fmt::fprintf::T">T</a>&... <em>args</em><span class="sig-paren">)</span> -> int<a class="headerlink" href="#_CPPv4I0Dp0EN3fmt7fprintfEiPNSt4FILEERK1SDpRK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Prints formatted data to the file <em>f</em>.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span><span class="o">::</span><span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span><span class="w"> </span><span class="s">"Don't %s!"</span><span class="p">,</span><span class="w"> </span><span class="s">"panic"</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T"> <span id="_CPPv3I0Dp0EN3fmt7sprintfERK1SDpRK1T"></span><span id="_CPPv2I0Dp0EN3fmt7sprintfERK1SDpRK1T"></span>template<typename <code class="sig-name descname">S</code>, typename ...<code class="sig-name descname">T</code>, typename <code class="sig-name descname">Char</code> = enable_if_t<detail::is_string<<a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::S">S</a>>::value, char_t<<a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::S">S</a>>>><br /><span class="target" id="printf_8h_1ad69b8f4ce3c9f39b062943851ce42626"></span>auto <code class="sig-prename descclassname"><a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::fmt">fmt</a><code class="sig-prename descclassname">::</code></code><code class="sig-name descname">sprintf</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::S">S</a> &<em>fmt</em>, <em class="property">const</em> <a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::T">T</a>&... <em>args</em><span class="sig-paren">)</span> -> std::basic_string<<a class="reference internal" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="fmt::sprintf::Char">Char</a>><a class="headerlink" href="#_CPPv4I0Dp0EN3fmt7sprintfENSt12basic_stringI4CharEERK1SDpRK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p><p><p>Formats arguments and returns the result as a string.</p> <p><strong>Example</strong>:</p> <div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">message</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">sprintf</span><span class="p">(</span><span class="s">"The answer is %d"</span><span class="p">,</span><span class="w"> </span><span class="mi">42</span><span class="p">);</span> </pre></div> </div> </p> </p> </dd></dl> </section> <section id="wchar-t-support"> <span id="xchar-api"></span><h2><code class="docutils literal notranslate"><span class="pre">wchar_t</span></code> Support<a class="headerlink" href="#wchar-t-support" title="Permalink to this headline">¶</a></h2> <p>The optional header <code class="docutils literal notranslate"><span class="pre">fmt/xchar.h</span></code> provides support for <code class="docutils literal notranslate"><span class="pre">wchar_t</span></code> and exotic character types.</p> <dl class="cpp struct"> <dt id="_CPPv4I0EN3fmt7is_charE"> <span id="_CPPv3I0EN3fmt7is_charE"></span><span id="_CPPv2I0EN3fmt7is_charE"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="structfmt_1_1is__char"></span><em class="property">struct </em><code class="sig-name descname">is_char</code> : <em class="property">public</em> std::false_type<a class="headerlink" href="#_CPPv4I0EN3fmt7is_charE" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Specifies if <code class="docutils literal notranslate"><span class="pre">T</span></code> is a character type. </p> <p>Can be specialized by users. </p> </dd></dl> <dl class="cpp type"> <dt id="_CPPv4N3fmt12wstring_viewE"> <span id="_CPPv3N3fmt12wstring_viewE"></span><span id="_CPPv2N3fmt12wstring_viewE"></span><span class="target" id="xchar_8h_1ad05bfd634fe8a5381ae220a52eaac7ba"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">wstring_view</code> = <a class="reference internal" href="#_CPPv4I0EN3fmt17basic_string_viewE" title="fmt::basic_string_view">basic_string_view</a><wchar_t><a class="headerlink" href="#_CPPv4N3fmt12wstring_viewE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp type"> <dt id="_CPPv4N3fmt15wformat_contextE"> <span id="_CPPv3N3fmt15wformat_contextE"></span><span id="_CPPv2N3fmt15wformat_contextE"></span><span class="target" id="xchar_8h_1a5c1e6b5dd3579e2734c620cb1977d671"></span><em class="property">using </em><code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">wformat_context</code> = buffer_context<wchar_t><a class="headerlink" href="#_CPPv4N3fmt15wformat_contextE" title="Permalink to this definition">¶</a><br /></dt> <dd></dd></dl> <dl class="cpp function"> <dt id="_CPPv4I0EN3fmt10to_wstringENSt7wstringERK1T"> <span id="_CPPv3I0EN3fmt10to_wstringERK1T"></span><span id="_CPPv2I0EN3fmt10to_wstringERK1T"></span>template<typename <code class="sig-name descname">T</code>><br /><span class="target" id="xchar_8h_1a97485c79bd9998f452c6aec356f13930"></span>auto <code class="sig-prename descclassname">fmt<code class="sig-prename descclassname">::</code></code><code class="sig-name descname">to_wstring</code><span class="sig-paren">(</span><em class="property">const</em> <a class="reference internal" href="#_CPPv4I0EN3fmt10to_wstringENSt7wstringERK1T" title="fmt::to_wstring::T">T</a> &<em>value</em><span class="sig-paren">)</span> -> std::wstring<a class="headerlink" href="#_CPPv4I0EN3fmt10to_wstringENSt7wstringERK1T" title="Permalink to this definition">¶</a><br /></dt> <dd><p>Converts <em>value</em> to <code class="docutils literal notranslate"><span class="pre">std::wstring</span></code> using the default format for type <em>T</em>. </p> </dd></dl> </section> <section id="compatibility-with-c-20-std-format"> <h2>Compatibility with C++20 <code class="docutils literal notranslate"><span class="pre">std::format</span></code><a class="headerlink" href="#compatibility-with-c-20-std-format" title="Permalink to this headline">¶</a></h2> <p>{fmt} implements nearly all of the <a class="reference external" href="https://en.cppreference.com/w/cpp/utility/format">C++20 formatting library</a> with the following differences:</p> <ul class="simple"> <li><p>Names are defined in the <code class="docutils literal notranslate"><span class="pre">fmt</span></code> namespace instead of <code class="docutils literal notranslate"><span class="pre">std</span></code> to avoid collisions with standard library implementations.</p></li> <li><p>Width calculation doesn’t use grapheme clusterization. The latter has been implemented in a separate branch but hasn’t been integrated yet.</p></li> <li><p>Most C++20 chrono types are not supported yet.</p></li> </ul> </section> </section> </div> </div> </div> <div class="footer" role="contentinfo"> © Copyright 2012-present, Victor Zverovich. Created using <a href="http://sphinx-doc.org/">Sphinx</a> 3.3.0. </div> <script src="_static/bootstrap.min.js"></script> </body> </html>