| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335 | <!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>Usage — fmt 9.1.0 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:     '9.1.0',        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">9.1.0                <span class="caret"></span></a>              <ul class="dropdown-menu" role="menu">                                <li><a href="https://fmt.dev/9.1.0">9.1.0</a></li>                                <li><a href="https://fmt.dev/9.0.0">9.0.0</a></li>                                <li><a href="https://fmt.dev/8.1.1">8.1.1</a></li>                              </ul>            </li>                                        <li><a href="contents.html">Contents</a></li>                                                      <li class="active"><a href="usage.html">Usage                <span class="sr-only">(current)</span></a></li>                                                      <li><a href="api.html">API</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="usage"><h1>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h1><p>To use the {fmt} library, add <code class="file docutils literal notranslate"><span class="pre">fmt/core.h</span></code>, <code class="file docutils literal notranslate"><span class="pre">fmt/format.h</span></code>,<code class="file docutils literal notranslate"><span class="pre">fmt/format-inl.h</span></code>, <code class="file docutils literal notranslate"><span class="pre">src/format.cc</span></code> and optionally other headersfrom a <a class="reference external" href="https://github.com/fmtlib/fmt/releases/latest">release archive</a> orthe <a class="reference external" href="https://github.com/fmtlib/fmt">Git repository</a> to your project.Alternatively, you can <a class="reference internal" href="#building"><span class="std std-ref">build the library with CMake</span></a>.</p><section id="building-the-library"><span id="building"></span><h2>Building the Library<a class="headerlink" href="#building-the-library" title="Permalink to this headline">¶</a></h2><p>The included <a class="reference external" href="https://github.com/fmtlib/fmt/blob/master/CMakeLists.txt">CMake build script</a> can be used to build the fmtlibrary on a wide range of platforms. CMake is freely available fordownload from <a class="reference external" href="https://www.cmake.org/download/">https://www.cmake.org/download/</a>.</p><p>CMake works by generating native makefiles or project files that canbe used in the compiler environment of your choice. The typicalworkflow starts with:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span>mkdir build          # Create a directory to hold the build output.cd buildcmake ..  # Generate native build scripts.</pre></div></div><p>where <code class="file docutils literal notranslate"><em><span class="pre"><path/to/fmt></span></em></code> is a path to the <code class="docutils literal notranslate"><span class="pre">fmt</span></code> repository.</p><p>If you are on a *nix system, you should now see a Makefile in thecurrent directory. Now you can build the library by running <strong class="command">make</strong>.</p><p>Once the library has been built you can invoke <strong class="command">make test</strong> to runthe tests.</p><p>You can control generation of the make <code class="docutils literal notranslate"><span class="pre">test</span></code> target with the <code class="docutils literal notranslate"><span class="pre">FMT_TEST</span></code>CMake option. This can be useful if you include fmt as a subdirectory inyour project but don’t want to add fmt’s tests to your <code class="docutils literal notranslate"><span class="pre">test</span></code> target.</p><p>If you use Windows and have Visual Studio installed, a <code class="file docutils literal notranslate"><span class="pre">FMT.sln</span></code>file and several <code class="file docutils literal notranslate"><span class="pre">.vcproj</span></code> files will be created. You can then build themusing Visual Studio or msbuild.</p><p>On Mac OS X with Xcode installed, an <code class="file docutils literal notranslate"><span class="pre">.xcodeproj</span></code> file will be generated.</p><p>To build a <a class="reference external" href="https://en.wikipedia.org/wiki/Library_%28computing%29#Shared_libraries">shared library</a> set the <code class="docutils literal notranslate"><span class="pre">BUILD_SHARED_LIBS</span></code> CMake variable to<code class="docutils literal notranslate"><span class="pre">TRUE</span></code>:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">cmake</span><span class="w"> </span><span class="o">-</span><span class="n">DBUILD_SHARED_LIBS</span><span class="o">=</span><span class="n">TRUE</span><span class="w"> </span><span class="p">...</span><span class="w"></span></pre></div></div><p>To build a <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">static</span> <span class="pre">library</span></code> with position independent code (required if the mainconsumer of the fmt library is a shared library i.e. a Python extension) set the<code class="docutils literal notranslate"><span class="pre">CMAKE_POSITION_INDEPENDENT_CODE</span></code> CMake variable to <code class="docutils literal notranslate"><span class="pre">TRUE</span></code>:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">cmake</span><span class="w"> </span><span class="o">-</span><span class="n">DCMAKE_POSITION_INDEPENDENT_CODE</span><span class="o">=</span><span class="n">TRUE</span><span class="w"> </span><span class="p">...</span><span class="w"></span></pre></div></div></section><section id="installing-the-library"><h2>Installing the Library<a class="headerlink" href="#installing-the-library" title="Permalink to this headline">¶</a></h2><p>After building the library you can install it on a Unix-like system by running<strong class="command">sudo make install</strong>.</p></section><section id="usage-with-cmake"><h2>Usage with CMake<a class="headerlink" href="#usage-with-cmake" title="Permalink to this headline">¶</a></h2><p>You can add the <code class="docutils literal notranslate"><span class="pre">fmt</span></code> library directory into your project and include it inyour <code class="docutils literal notranslate"><span class="pre">CMakeLists.txt</span></code> file:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">add_subdirectory</span><span class="p">(</span><span class="n">fmt</span><span class="p">)</span><span class="w"></span></pre></div></div><p>or</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">add_subdirectory</span><span class="p">(</span><span class="n">fmt</span><span class="w"> </span><span class="n">EXCLUDE_FROM_ALL</span><span class="p">)</span><span class="w"></span></pre></div></div><p>to exclude it from <code class="docutils literal notranslate"><span class="pre">make</span></code>, <code class="docutils literal notranslate"><span class="pre">make</span> <span class="pre">all</span></code>, or <code class="docutils literal notranslate"><span class="pre">cmake</span> <span class="pre">--build</span> <span class="pre">.</span></code>.</p><p>You can detect and use an installed version of {fmt} as follows:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">find_package</span><span class="p">(</span><span class="n">fmt</span><span class="p">)</span><span class="w"></span><span class="n">target_link_libraries</span><span class="p">(</span><span class="o"><</span><span class="n">your</span><span class="o">-</span><span class="n">target</span><span class="o">></span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">fmt</span><span class="p">)</span><span class="w"></span></pre></div></div><p>Setting up your target to use a header-only version of <code class="docutils literal notranslate"><span class="pre">fmt</span></code> is equally easy:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">target_link_libraries</span><span class="p">(</span><span class="o"><</span><span class="n">your</span><span class="o">-</span><span class="n">target</span><span class="o">></span><span class="w"> </span><span class="n">PRIVATE</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">fmt</span><span class="o">-</span><span class="n">header</span><span class="o">-</span><span class="n">only</span><span class="p">)</span><span class="w"></span></pre></div></div></section><section id="usage-with-build2"><h2>Usage with build2<a class="headerlink" href="#usage-with-build2" title="Permalink to this headline">¶</a></h2><p>You can use <a class="reference external" href="https://build2.org">build2</a>, a dependency manager and abuild-system combined, to use <code class="docutils literal notranslate"><span class="pre">fmt</span></code>.</p><p>Currently this package is available in these package repositories:</p><ul class="simple"><li><p><strong>https://cppget.org/fmt/</strong> for released and published versions.</p></li><li><p><a class="reference external" href="https://github.com/build2-packaging/fmt.git">The git repository with the sources of the build2 package of fmt</a>for unreleased or custom revisions of <code class="docutils literal notranslate"><span class="pre">fmt</span></code>.</p></li></ul><p><strong>Usage:</strong></p><ul class="simple"><li><p><code class="docutils literal notranslate"><span class="pre">build2</span></code> package name: <code class="docutils literal notranslate"><span class="pre">fmt</span></code></p></li><li><p>Library target name : <code class="docutils literal notranslate"><span class="pre">lib{fmt}</span></code></p></li></ul><p>For example, to make your <code class="docutils literal notranslate"><span class="pre">build2</span></code> project depend on <code class="docutils literal notranslate"><span class="pre">fmt</span></code>:</p><ul><li><p>Add one of the repositories to your configurations, or in your<code class="docutils literal notranslate"><span class="pre">repositories.manifest</span></code>, if not already there:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="o">:</span><span class="w"></span><span class="nl">role</span><span class="p">:</span><span class="w"> </span><span class="n">prerequisite</span><span class="w"></span><span class="nl">location</span><span class="p">:</span><span class="w"> </span><span class="n">https</span><span class="o">:</span><span class="c1">//pkg.cppget.org/1/stable</span></pre></div></div></li><li><p>Add this package as a dependency to your <code class="docutils literal notranslate"><span class="pre">./manifest</span></code> file(example for <code class="docutils literal notranslate"><span class="pre">v7.0.x</span></code>):</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="nl">depends</span><span class="p">:</span><span class="w"> </span><span class="n">fmt</span><span class="w"> </span><span class="o">~</span><span class="mf">7.0.0</span><span class="w"></span></pre></div></div></li><li><p>Import the target and use it as a prerequisite to your own targetusing <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">fmt</span></code> in the appropriate <code class="docutils literal notranslate"><span class="pre">buildfile</span></code>:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">import</span><span class="w"> </span><span class="n">fmt</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">lib</span><span class="p">{</span><span class="n">fmt</span><span class="p">}</span><span class="w"></span><span class="n">lib</span><span class="p">{</span><span class="n">mylib</span><span class="p">}</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">cxx</span><span class="p">{</span><span class="o">**</span><span class="p">}</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="n">$fmt</span><span class="w"></span></pre></div></div></li></ul><p>Then build your project as usual with <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">b</span></code> or <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">bdep</span> <span class="pre">update</span></code>.</p><p>For <code class="docutils literal notranslate"><span class="pre">build2</span></code> newcomers or to get more details and use cases, you can read the<code class="docutils literal notranslate"><span class="pre">build2</span></code><a class="reference external" href="https://build2.org/build2-toolchain/doc/build2-toolchain-intro.xhtml">toolchain introduction</a>.</p></section><section id="building-the-documentation"><h2>Building the Documentation<a class="headerlink" href="#building-the-documentation" title="Permalink to this headline">¶</a></h2><p>To build the documentation you need the following software installed on yoursystem:</p><ul><li><p><a class="reference external" href="https://www.python.org/">Python</a> with pip and virtualenv</p></li><li><p><a class="reference external" href="http://www.stack.nl/~dimitri/doxygen/">Doxygen</a></p></li><li><p><a class="reference external" href="http://lesscss.org/">Less</a> with <code class="docutils literal notranslate"><span class="pre">less-plugin-clean-css</span></code>.Ubuntu doesn’t package the <code class="docutils literal notranslate"><span class="pre">clean-css</span></code> plugin so you should use <code class="docutils literal notranslate"><span class="pre">npm</span></code>instead of <code class="docutils literal notranslate"><span class="pre">apt</span></code> to install both <code class="docutils literal notranslate"><span class="pre">less</span></code> and the plugin:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">sudo</span><span class="w"> </span><span class="n">npm</span><span class="w"> </span><span class="n">install</span><span class="w"> </span><span class="o">-</span><span class="n">g</span><span class="w"> </span><span class="n">less</span><span class="w"> </span><span class="n">less</span><span class="o">-</span><span class="n">plugin</span><span class="o">-</span><span class="n">clean</span><span class="o">-</span><span class="n">css</span><span class="p">.</span><span class="w"></span></pre></div></div></li></ul><p>First generate makefiles or project files using CMake as described inthe previous section. Then compile the <code class="docutils literal notranslate"><span class="pre">doc</span></code> target/project, for example:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">make</span><span class="w"> </span><span class="n">doc</span><span class="w"></span></pre></div></div><p>This will generate the HTML documentation in <code class="docutils literal notranslate"><span class="pre">doc/html</span></code>.</p></section><section id="conda"><h2>Conda<a class="headerlink" href="#conda" title="Permalink to this headline">¶</a></h2><p>fmt can be installed on Linux, macOS and Windows with<a class="reference external" href="https://docs.conda.io/en/latest/">Conda</a>, using its<a class="reference external" href="https://conda-forge.org">conda-forge</a><a class="reference external" href="https://github.com/conda-forge/fmt-feedstock">package</a>, as follows:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">conda</span><span class="w"> </span><span class="n">install</span><span class="w"> </span><span class="o">-</span><span class="n">c</span><span class="w"> </span><span class="n">conda</span><span class="o">-</span><span class="n">forge</span><span class="w"> </span><span class="n">fmt</span><span class="w"></span></pre></div></div></section><section id="vcpkg"><h2>Vcpkg<a class="headerlink" href="#vcpkg" title="Permalink to this headline">¶</a></h2><p>You can download and install fmt using the <a class="reference external" href="https://github.com/Microsoft/vcpkg">vcpkg</a> dependency manager:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">git</span><span class="w"> </span><span class="n">clone</span><span class="w"> </span><span class="n">https</span><span class="o">:</span><span class="c1">//github.com/Microsoft/vcpkg.git</span><span class="n">cd</span><span class="w"> </span><span class="n">vcpkg</span><span class="w"></span><span class="p">.</span><span class="o">/</span><span class="n">bootstrap</span><span class="o">-</span><span class="n">vcpkg</span><span class="p">.</span><span class="n">sh</span><span class="w"></span><span class="p">.</span><span class="o">/</span><span class="n">vcpkg</span><span class="w"> </span><span class="n">integrate</span><span class="w"> </span><span class="n">install</span><span class="w"></span><span class="p">.</span><span class="o">/</span><span class="n">vcpkg</span><span class="w"> </span><span class="n">install</span><span class="w"> </span><span class="n">fmt</span><span class="w"></span></pre></div></div><p>The fmt port in vcpkg is kept up to date by Microsoft team members and communitycontributors. If the version is out of date, please <a class="reference external" href="https://github.com/Microsoft/vcpkg">create an issue or pullrequest</a> on the vcpkg repository.</p></section><section id="lhelper"><h2>LHelper<a class="headerlink" href="#lhelper" title="Permalink to this headline">¶</a></h2><p>You can download and install fmt using<a class="reference external" href="https://github.com/franko/lhelper">lhelper</a> dependency manager:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">lhelper</span><span class="w"> </span><span class="n">activate</span><span class="w"> </span><span class="o"><</span><span class="n">some</span><span class="o">-</span><span class="n">environment</span><span class="o">></span><span class="w"></span><span class="n">lhelper</span><span class="w"> </span><span class="n">install</span><span class="w"> </span><span class="n">fmt</span><span class="w"></span></pre></div></div><p>All the recipes for lhelper are kept in the<a class="reference external" href="https://github.com/franko/lhelper-recipes">lhelper’s recipe</a> repository.</p></section><section id="android-ndk"><h2>Android NDK<a class="headerlink" href="#android-ndk" title="Permalink to this headline">¶</a></h2><p>fmt provides <a class="reference external" href="https://github.com/fmtlib/fmt/blob/master/support/Android.mk">Android.mk file</a> that can be used to build the librarywith <a class="reference external" href="https://developer.android.com/tools/sdk/ndk/index.html">Android NDK</a>.For an example of using fmt with Android NDK, see the<a class="reference external" href="https://github.com/fmtlib/android-ndk-example">android-ndk-example</a>repository.</p></section><section id="homebrew"><h2>Homebrew<a class="headerlink" href="#homebrew" title="Permalink to this headline">¶</a></h2><p>fmt can be installed on OS X using <a class="reference external" href="https://brew.sh/">Homebrew</a>:</p><div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">brew</span><span class="w"> </span><span class="n">install</span><span class="w"> </span><span class="n">fmt</span><span class="w"></span></pre></div></div></section></section>    </div>  </div></div>    <div class="footer" role="contentinfo">        © Copyright 2012-present, Victor Zverovich.      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