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](
https://github.com/fmtlib/fmt/releases/latest) or the [git repository](
https://github.com/fmtlib/fmt) to your project. Alternatively, you can
[build the library with CMake](#building).

## Building the Library {#building}

The included [CMake build
script](https://github.com/fmtlib/fmt/blob/master/CMakeLists.txt) 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](https://en.wikipedia.org/wiki/Library_%28computing%29#Shared_libraries)
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](https://build2.org), 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](https://github.com/build2-packaging/fmt.git) 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](https://build2.org/build2-toolchain/doc/build2-toolchain-intro.xhtml).

## 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](https://www.python.org/) with pip and virtualenv

- [Doxygen](http://www.stack.nl/~dimitri/doxygen/)

- [Less](http://lesscss.org/) 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](https://docs.conda.io/en/latest/), using its
[conda-forge](https://conda-forge.org)
[package](https://github.com/conda-forge/fmt-feedstock), as follows:

    conda install -c conda-forge fmt

## Vcpkg

You can download and install fmt using the
[vcpkg](https://github.com/Microsoft/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](https://github.com/Microsoft/vcpkg) on the vcpkg
repository.

## LHelper

You can download and install fmt using
[lhelper](https://github.com/franko/lhelper) dependency manager:

    lhelper activate <some-environment>
    lhelper install fmt

All the recipes for lhelper are kept in the [lhelper\'s
recipe](https://github.com/franko/lhelper-recipes) repository.

## Android NDK

fmt provides [Android.mk
file](https://github.com/fmtlib/fmt/blob/master/support/Android.mk) that
can be used to build the library with [Android
NDK](https://developer.android.com/tools/sdk/ndk/index.html). For an
example of using fmt with Android NDK, see the
[android-ndk-example](https://github.com/fmtlib/android-ndk-example)
repository.

## Homebrew

fmt can be installed on OS X using [Homebrew](https://brew.sh/):

    brew install fmt