source/misc/embedded_libs/fmt-11.0.2/doc/index.md

--- hide: - navigation - toc --- # A modern formatting library <div class="features-container"> <div class="feature"> <h2>Safety</h2> <p> Inspired by Python's formatting facility, {fmt} provides a safe replacement for the <code>printf</code> family of functions. Errors in format strings, which are a common source of vulnerabilities in C, are <b>reported at compile time</b>. For example: <pre><code class="language-cpp" >fmt::format("{:d}", "I am not a number");</code></pre> will give a compile-time error because <code>d</code> is not a valid format specifier for strings. APIs like <a href="api/#format"> <code>fmt::format</code></a> <b>prevent buffer overflow errors</b> via automatic memory management. </p> <a href="api#compile-time-checks">→ Learn more</a> </div> <div class="feature"> <h2>Extensibility</h2> <p> Formatting of most <b>standard types</b>, including all containers, dates, and times is <b>supported out-of-the-box</b>. For example: <pre><code class="language-cpp" >fmt::print("{}", std::vector{1, 2, 3});</code></pre> prints the vector in a JSON-like format: <pre><code>[1, 2, 3]</code></pre> You can <b>make your own types formattable</b> and even make compile-time checks work for them. </p> <a href="api#udt">→ Learn more</a> </div> <div class="feature"> <h2>Performance</h2> <p> {fmt} can be anywhere from <b>tens of percent to 20-30 times faster</b> than iostreams and <code>sprintf</code>, especially for numeric formatting. <a href="https://github.com/fmtlib/fmt?tab=readme-ov-file#benchmarks"> <img src="perf.svg"> </a> The library <b>minimizes dynamic memory allocations</b> and can optionally <a href="api#compile-api">compile format strings</a> to optimal code. </p> </div> <div class="feature"> <h2>Unicode support</h2> <p> {fmt} provides <b>portable Unicode support</b> on major operating systems with UTF-8 and <code>char</code> strings. For example: <pre><code class="language-cpp" >fmt::print("Слава Україні!");</code></pre> will be printed correctly on Linux, macOS, and even Windows console, irrespective of the codepages. </p> <p> The default is <b>locale-independent</b>, but you can opt into localized formatting and {fmt} makes it work with Unicode, addressing issues in the standard libary. </p> </div> <div class="feature"> <h2>Fast compilation</h2> <p> The library makes extensive use of <b>type erasure</b> to achieve fast compilation. <code>fmt/base.h</code> provides a subset of the API with <b>minimal include dependencies</b> and enough functionality to replace all uses of <code>*printf</code>. </p> <p> Code using {fmt} is usually several times faster to compile than the equivalent iostreams code, and while <code>printf</code> compiles faster still, the gap is narrowing. </p> <a href= "https://github.com/fmtlib/fmt?tab=readme-ov-file#compile-time-and-code-bloat"> → Learn more</a> </div> <div class="feature"> <h2>Small binary footprint</h2> <p> Type erasure is also used to prevent template bloat, resulting in <b>compact per-call binary code</b>. For example, a call to <code>fmt::print</code> with a single argument is just <a href="https://godbolt.org/g/TZU4KF">a few instructions</a>, comparable to <code>printf</code> despite adding runtime safety, and much smaller than the equivalent iostreams code. </p> <p> The library itself has small binary footprint and some components such as floating-point formatting can be disabled to make it even smaller for resource-constrained devices. </p> </div> <div class="feature"> <h2>Portability</h2> <p> {fmt} has a <b>small self-contained codebase</b> with the core consisting of just three headers and no external dependencies. </p> <p> The library is highly portable and requires only a minimal <b>subset of C++11</b> features which are available in GCC 4.8, Clang 3.4, MSVC 19.0 (2015) and later. Newer compiler and standard library features are used if available, and enable additional functionality. </p> <p> Where possible, the output of formatting functions is <b>consistent across platforms</b>. </p> </p> </div> <div class="feature"> <h2>Open source</h2> <p> {fmt} is in the top hundred open-source C++ libraries on GitHub and has <a href="https://github.com/fmtlib/fmt/graphs/contributors">hundreds of all-time contributors</a>. </p> <p> The library is distributed under a permissive MIT <a href="https://github.com/fmtlib/fmt#license">license</a> and is <b>relied upon by many open-source projects</b>, including Blender, PyTorch, Apple's FoundationDB, Windows Terminal, MongoDB, and others. </p> </div> </div>