fmt/doc/usage.md

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.

run in 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{.interpreted-text role="command"}.

Once the library has been built you can invoke make test{.interpreted-text role="command"} 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{.interpreted-text role="file"} 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]{.title-ref} 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{.interpreted-text role="command"}.

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]{.title-ref} in the appropriate buildfile:

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

Then build your project as usual with [b]{.title-ref} or [bdep update]{.title-ref}.

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

Usage with Meson

[Meson's WrapDB <https://mesonbuild.com/Wrapdb-projects.html>]{.title-ref} 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