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GeezerVison is showing android.googlesource.com — platform/external/fmtlib - Git at Google Clone this repo:
{fmt} is an open-source formatting library providing a fast and safe alternative to C stdio and C++ iostreams. If you like this project, please consider donating to one of the funds that help victims of the war in Ukraine: https://www.stopputin.net/. Q&A: ask questions on StackOverflow with the tag fmt. Try {fmt} in Compiler Explorer. Features
See the documentation for more details. ExamplesPrint to stdout (run) #include <fmt/core.h> int main() { fmt::print("Hello, world!\n"); } Format a string (run) std::string s = fmt::format("The answer is {}.", 42); // s == "The answer is 42." Format a string using positional arguments (run) std::string s = fmt::format("I'd rather be {1} than {0}.", "right", "happy"); // s == "I'd rather be happy than right." Print dates and times (run) #include <fmt/chrono.h> int main() { auto now = std::chrono::system_clock::now(); fmt::print("Date and time: {}\n", now); fmt::print("Time: {:%H:%M}\n", now); } Output: Date and time: 2023-12-26 19:10:31.557195597 Time: 19:10 Print a container (run) #include <vector> #include <fmt/ranges.h> int main() { std::vector<int> v = {1, 2, 3}; fmt::print("{}\n", v); } Output: [1, 2, 3] Check a format string at compile time std::string s = fmt::format("{:d}", "I am not a number"); This gives a compile-time error in C++20 because Write a file from a single thread #include <fmt/os.h> int main() { auto out = fmt::output_file("guide.txt"); out.print("Don't {}", "Panic"); } This can be 5 to 9 times faster than fprintf. Print with colors and text styles #include <fmt/color.h> int main() { fmt::print(fg(fmt::color::crimson) | fmt::emphasis::bold, "Hello, {}!\n", "world"); fmt::print(fg(fmt::color::floral_white) | bg(fmt::color::slate_gray) | fmt::emphasis::underline, "Olá, {}!\n", "Mundo"); fmt::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic, "你好{}！\n", "世界"); } Output on a modern terminal with Unicode support: BenchmarksSpeed tests
{fmt} is the fastest of the benchmarked methods, ~20% faster than The above results were generated by building {fmt} is up to 20-30x faster than
Compile time and code bloatThe script bloat-test.py from format-benchmark tests compile time and code bloat for nontrivial projects. It generates 100 translation units and uses Optimized build (-O3)
{fmt} is fast to compile and is comparable to Non-optimized build
Running the testsPlease refer to Building the library for instructions on how to build the library and run the unit tests. Benchmarks reside in a separate repository, format-benchmarks, so to run the benchmarks you first need to clone this repository and generate Makefiles with CMake: $ git clone --recursive https://github.com/fmtlib/format-benchmark.git $ cd format-benchmark $ cmake . Then you can run the speed test: $ make speed-test or the bloat test: $ make bloat-test Migrating codeclang-tidy v18 provides the modernize-use-std-print check that is capable of converting occurrences of Notable projects using this library
If you are aware of other projects using this library, please let me know by email or by submitting an issue. MotivationSo why yet another formatting library? There are plenty of methods for doing this task, from standard ones like the printf family of function and iostreams to Boost Format and FastFormat libraries. The reason for creating a new library is that every existing solution that I found either had serious issues or didn't provide all the features I needed. printfThe good thing about iostreamsThe main issue with iostreams is best illustrated with an example: std::cout << std::setprecision(2) << std::fixed << 1.23456 << "\n"; which is a lot of typing compared to printf: printf("%.2f\n", 1.23456); Matthew Wilson, the author of FastFormat, called this "chevron hell". iostreams don't support positional arguments by design. The good part is that iostreams support user-defined types and are safe although error handling is awkward. Boost FormatThis is a very powerful library that supports both FastFormatThis is an interesting library that is fast, safe and has positional arguments. However, it has significant limitations, citing its author:
It is also quite big and has a heavy dependency, on STLSoft, which might be too restrictive for use in some projects. Boost Spirit.KarmaThis is not a formatting library but I decided to include it here for completeness. As iostreams, it suffers from the problem of mixing verbatim text with arguments. The library is pretty fast, but slower on integer formatting than License{fmt} is distributed under the MIT license. Documentation LicenseThe Format String Syntax section in the documentation is based on the one from Python string module documentation. For this reason, the documentation is distributed under the Python Software Foundation license available in doc/python-license.txt. It only applies if you distribute the documentation of {fmt}. MaintainersThe {fmt} library is maintained by Victor Zverovich (vitaut) with contributions from many other people. See Contributors and Releases for some of the names. Let us know if your contribution is not listed or mentioned incorrectly and we'll make it right. Security PolicyTo report a security issue, please disclose it at security advisory. This project is maintained by a team of volunteers on a reasonable-effort basis. As such, please give us at least 90 days to work on a fix before public exposure. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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