format_utf8

Single header extension to std::format for char8_t, char16_t, char32_t, u8string and u8string_view.

Notes:

1. Single character values are always intepreted as numeric values.
2. If the unicode character is desired then use the string form with that single character.
3. char8_t, char16_t, and char32_t support their equivalent uintN_t formatting specifiers.
4. u8string and u8string_view do not currently support formatting specifiers, only outputting as-is.
5. When compiling for MSVC, ensure compile flag /utf-8 is used.
6. On godbolt, <format> + <iostream> requires c++20; gcc(x86-64 13.3), clang(x86-64 trunk : 19.1.0 compiler errors), and msvc (x64 19.32)
7. On godbolt, <print> requires c++23; gcc(x86-64 14.1), clang(x86-64 latest : 19.1.0 missing ), and msvc (x64 19.37)

Examples:

#include <print>
#include <string>
#include <string_view>
#include "format_utf8.hpp"

int main() {
    char8_t c8 = 0x41;
    char16_t c16 = 0x42;
    char32_t c32 = 0x0001F600;
    std::u8string s8{u8"hello😀"};
    std::u8string_view sv8{s8};
    std::string test{"hello😀"};

    std::println("Normal char strings");
    std::println("{}", "hello😀");
    std::println("{}", "\U0001F600");
    std::println("");

    std::println("char8_t");
    std::println("{}", c8);
    std::println("{:#x}", c8);
    std::println("{:05d}", c8);
    std::println("");

    std::println("char16_t");
    std::println("{}", c16);
    std::println("{:#x}", c16);
    std::println("{:05d}", c16);
    std::println("");

    std::println("char32_t");
    std::println("{}", c32);
    std::println("{:#x}", c32);
    std::println("{:#010x}", c32);
    std::println("{:d}", c32);
    std::println("{:08d}", c32);
    std::println("");

    std::println("utf-8 strings");
    std::println("{}", u8"hello 😀 there");
    std::println("{}", s8);
    std::println("{}", std::u8string{u8"hello😀"});
    std::println("{}", std::u8string_view{u8"hello😀"});
    std::println("");

    return 0;
}

#include <format>
#include <iostream>
#include <string>
#include <string_view>
#include "format_utf8.hpp"

int main() {
    char8_t c8 = 0x41;
    char16_t c16 = 0x42;
    char32_t c32 = 0x0001F600;
    std::u8string s8{u8"hello😀"};
    std::u8string_view sv8{s8};

    std::cout << std::format("Normal char strings\n");
    std::cout << std::format("{}\n", "hello😀");
    std::cout << std::format("{}\n", "\U0001F600");
    std::cout << std::format("\n");

    std::cout << std::format("char8_t\n");
    std::cout << std::format("{}\n", c8);
    std::cout << std::format("{:#x}\n", c8);
    std::cout << std::format("{:05d}\n", c8);
    std::cout << std::format("\n");

    std::cout << std::format("char16_t\n");
    std::cout << std::format("{}\n", c16);
    std::cout << std::format("{:#x}\n", c16);
    std::cout << std::format("{:05d}\n", c16);
    std::cout << std::format("\n");

    std::cout << std::format("char32_t\n");
    std::cout << std::format("{}\n", c32);
    std::cout << std::format("{:#x}\n", c32);
    std::cout << std::format("{:#010x}\n", c32);
    std::cout << std::format("{:d}\n", c32);
    std::cout << std::format("{:08d}\n", c32);
    std::cout << std::format("\n");

    std::cout << std::format("utf-8 strings\n");
    std::cout << std::format("{}\n", u8"hello 😀 there");
    std::cout << std::format("{}\n", s8);
    std::cout << std::format("{}\n", std::u8string{u8"hello😀"});
    std::cout << std::format("{}\n", std::u8string_view{u8"hello😀"});
    std::cout << std::format("\n");

    return 0;
}