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| Regular expressions library(C++11) | |||||||||||||||||||||||||
| Formatting library(C++20) | |||||||||||||||||||||||||
| Null-terminated sequence utilities | |||||||||||||||||||||||||
| Byte strings | |||||||||||||||||||||||||
| Multibyte strings | |||||||||||||||||||||||||
| Wide strings | |||||||||||||||||||||||||
| Primitive numeric conversions | |||||||||||||||||||||||||
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| Text encoding identifications | |||||||||||||||||||||||||
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Defined in header <codecvt> | ||
enum codecvt_mode{ consume_header=4, | (since C++11) (deprecated in C++17) (removed in C++26) | |
The facetsstd::codecvt_utf8,std::codecvt_utf16, andstd::codecvt_utf8_utf16 accept an optional value of typestd::codecvt_mode as a template argument, which specifies optional features of the unicode string conversion.
Defined in header <locale> | |
| Enumerator | Meaning |
little_endian | assume the input is in little-endian byte order (applies to UTF-16 input only, the default is big-endian) |
consume_header | consume the byte order mark, if present at the start of input sequence, and (in case of UTF-16), rely on the byte order it specifies for decoding the rest of the input |
generate_header | output the byte order mark at the start of the output sequence |
The recognized byte order marks are:
0xfe 0xff | UTF-16 big-endian |
0xff 0xfe | UTF-16 little-endian |
0xef 0xbb 0xbf | UTF-8 (no effect on endianness) |
Ifstd::consume_header is not selected when reading a file beginning with byte order mark, the Unicode character U+FEFF (Zero width non-breaking space) will be read as the first character of the string content.
The following example demonstrates consuming the UTF-8 BOM:
#include <codecvt>#include <cwchar>#include <fstream>#include <iostream>#include <locale>#include <string> int main(){// UTF-8 data with BOMstd::ofstream{"text.txt"}<<"\ufeffz\u6c34\U0001d10b"; // read the UTF-8 file, skipping the BOMstd::wifstream fin{"text.txt"}; fin.imbue(std::locale(fin.getloc(), newstd::codecvt_utf8<wchar_t,0x10ffff, std::consume_header>)); for(wchar_t c; fin.get(c);)std::cout<<std::hex<<std::showbase<<(std::wint_t)c<<'\n';}
Output:
0x7a0x6c340x1d10b
| converts between character encodings, including UTF-8, UTF-16, UTF-32 (class template)[edit] | |
(C++11)(deprecated in C++17)(removed in C++26) | converts between UTF-8 and UCS-2/UCS-4 (class template)[edit] |
(C++11)(deprecated in C++17)(removed in C++26) | converts between UTF-16 and UCS-2/UCS-4 (class template)[edit] |
(C++11)(deprecated in C++17)(removed in C++26) | converts between UTF-8 and UTF-16 (class template)[edit] |
