This is the C++11 template based header only library under Windows/Linux/MacOs to convert UFT-8/16/32 symbols and strings. The library transparently support wchar_t as UTF-16 for Windows and UTF-32 for Linux and MacOs.
UTF-8 and UTF-32 (UCS-32) both support 31 bit wide code points [0‥0x7FFFFFFF]with no restriction. UTF-16 supports only unicode code points [0‥0x10FFFF], where high [0xD800‥0xDBFF] and low [0xDC00‥0xDFFF] surrogate regions are prohibited.
The maximum UTF-16 symbol size is 2 words (4 bytes, both words should be in the surrogate region). UFT-32 (UCS-32) is always 1 word (4 bytes). UTF-8 has the maximum symbol size (see conversion table for details):
- 4 bytes for unicode code points
- 6 bytes for 31bit code points
| High\Low | DC00 | DC01 | … | DFFF |
|---|---|---|---|---|
| D800 | 010000 | 010001 | … | 0103FF |
| D801 | 010400 | 010401 | … | 0107FF |
| ⋮ | ⋮ | ⋮ | ⋱ | ⋮ |
| DBFF | 10FC00 | 10FC01 | … | 10FFFF |
Tested on following compilers:
- Visual Studio 2013 v12.0.40629.00 Update 5
- Visual Studio 2015 v14.0.25431.01 Update 3
- Visual Studio 2017 v15.6.7
- Visual Studio 2019 v16.0.3
- GNU v5.4.0
- Clang v6.0.1
- Apple Clang v10.0.1
// यूनिकोड
static char const u8s[] = "\xE0\xA4\xAF\xE0\xA5\x82\xE0\xA4\xA8\xE0\xA4\xBF\xE0\xA4\x95\xE0\xA5\x8B\xE0\xA4\xA1";
using namespace ww898::utf;
std::u16string u16;
convz<utf_selector_t<decltype(*u8s)>, utf16>(u8s, std::back_inserter(u16));
std::u32string u32;
conv<utf16, utf_selector_t<decltype(u32)::value_type>>(u16.begin(), u16.end(), std::back_inserter(u32));
std::vector<char> u8;
convz<utf32, utf8>(u32.data(), std::back_inserter(u8));
std::wstring uw;
conv<utf8, utfw>(u8s, u8s + sizeof(u8s), std::back_inserter(uw));
auto u8r = conv<char>(uw);
auto u16r = conv<char16_t>(u16);
auto uwr = convz<wchar_t>(u8s);
auto u32r = conv<char32_t>(std::string_view(u8r.data(), u8r.size())); // C++17 only
static_assert(std::is_same<utf_selector<decltype(*u8s)>, utf_selector<decltype(u8)::value_type>>::value, "Fail");
static_assert(
std::is_same<utf_selector_t<decltype(u16)::value_type>, utf_selector_t<decltype(uw)::value_type>>::value !=
std::is_same<utf_selector_t<decltype(u32)::value_type>, utf_selector_t<decltype(uw)::value_type>>::value, "Fail");