Usage — fmt 10.2.1 documentation
Author: Victor Zverovich
Description: Small, safe and fast formatting library
Keywords: C++, formatting, printf, string, library

# Usage

To use the {fmt} library, add `fmt/core.h`, `fmt/format.h`, `fmt/format-inl.h`, `src/format.cc` and optionally other headers from a release archive or the Git repository to your project. Alternatively, you can build the library with CMake.

## Building the Library

The included CMake build script can be used to build the fmt library on a wide range of platforms. CMake is freely available for download from https://www.cmake.org/download/.

CMake works by generating native makefiles or project files that can be used in the compiler environment of your choice. The typical workflow starts with:

    mkdir build          # Create a directory to hold the build output.
    cd build
    cmake ..  # Generate native build scripts.

where `<path/to/fmt>` is a path to the `fmt` repository.

If you are on a *nix system, you should now see a Makefile in the current directory. Now you can build the library by running make.

Once the library has been built you can invoke make test to run the tests.

You can control generation of the make `test` target with the `FMT_TEST` CMake option. This can be useful if you include fmt as a subdirectory in your project but don’t want to add fmt’s tests to your `test` target.

If you use Windows and have Visual Studio installed, a `FMT.sln` file and several `.vcproj` files will be created. You can then build them using Visual Studio or msbuild.

On Mac OS X with Xcode installed, an `.xcodeproj` file will be generated.

To build a shared library set the `BUILD_SHARED_LIBS` CMake variable to `TRUE`:

    cmake -DBUILD_SHARED_LIBS=TRUE ...

To build a `static library` with position independent code (required if the main consumer of the fmt library is a shared library i.e. a Python extension) set the `CMAKE_POSITION_INDEPENDENT_CODE` CMake variable to `TRUE`:

    cmake -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ...

## Installing the Library

After building the library you can install it on a Unix-like system by running sudo make install.

## Usage with CMake

You can add the `fmt` library directory into your project and include it in your `CMakeLists.txt` file:

    add_subdirectory(fmt)

or

    add_subdirectory(fmt EXCLUDE_FROM_ALL)

to exclude it from `make`, `make all`, or `cmake --build .`.

You can detect and use an installed version of {fmt} as follows:

    find_package(fmt)
    target_link_libraries(<your-target> fmt::fmt)

Setting up your target to use a header-only version of `fmt` is equally easy:

    target_link_libraries(<your-target> PRIVATE fmt::fmt-header-only)

## Usage with build2

You can use build2, a dependency manager and a build-system combined, to use `fmt`.

Currently this package is available in these package repositories:

- https://cppget.org/fmt/ for released and published versions.

- The git repository with the sources of the build2 package of fmt for unreleased or custom revisions of `fmt`.

Usage:

- `build2` package name: `fmt`

- Library target name : `lib{fmt}`

For example, to make your `build2` project depend on `fmt`:

- Add one of the repositories to your configurations, or in your `repositories.manifest`, if not already there:

      :
      role: prerequisite
      location: https://pkg.cppget.org/1/stable

- Add this package as a dependency to your `./manifest` file (example for `v7.0.x`):

      depends: fmt ~7.0.0

- Import the target and use it as a prerequisite to your own target using `fmt` in the appropriate `buildfile`:

      import fmt = fmt%lib{fmt}
      lib{mylib} : cxx{**} ... $fmt

Then build your project as usual with `b` or `bdep update`.

For `build2` newcomers or to get more details and use cases, you can read the `build2` toolchain introduction.

## Usage with Meson

`Meson's WrapDB` includes a `fmt` package, which repackages fmt to be built by Meson as a subproject.

Usage:

- Install the `fmt` subproject from the WrapDB by running:

      meson wrap install fmt

  from the root of your project.

- In your project’s `meson.build` file, add an entry for the new subproject:

      fmt = subproject('fmt')
      fmt_dep = fmt.get_variable('fmt_dep')

- Include the new dependency object to link with fmt:

      my_build_target = executable('name', 'src/main.cc', dependencies: [fmt_dep])

Options:

If desired, `fmt` may be built as a static library, or as a header-only library.

For a static build, use the following subproject definition:

    fmt = subproject('fmt', default_options: 'default_library=static')
    fmt_dep = fmt.get_variable('fmt_dep')

For the header-only version, use:

    fmt = subproject('fmt')
    fmt_dep = fmt.get_variable('fmt_header_only_dep')

## Building the Documentation

To build the documentation you need the following software installed on your system:

- Python with pip and virtualenv

- Doxygen

- Less with `less-plugin-clean-css`. Ubuntu doesn’t package the `clean-css` plugin so you should use `npm` instead of `apt` to install both `less` and the plugin:

      sudo npm install -g less less-plugin-clean-css.

First generate makefiles or project files using CMake as described in the previous section. Then compile the `doc` target/project, for example:

    make doc

This will generate the HTML documentation in `doc/html`.

## Conda

fmt can be installed on Linux, macOS and Windows with Conda, using its conda-forge package, as follows:

    conda install -c conda-forge fmt

## Vcpkg

You can download and install fmt using the vcpkg dependency manager:

    git clone https://github.com/Microsoft/vcpkg.git
    cd vcpkg
    ./bootstrap-vcpkg.sh
    ./vcpkg integrate install
    ./vcpkg install fmt

The fmt port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

## LHelper

You can download and install fmt using lhelper dependency manager:

    lhelper activate <some-environment>
    lhelper install fmt

All the recipes for lhelper are kept in the lhelper’s recipe repository.

## Android NDK

fmt provides Android.mk file that can be used to build the library with Android NDK. For an example of using fmt with Android NDK, see the android-ndk-example repository.

## Homebrew

fmt can be installed on OS X using Homebrew:

    brew install fmt