std::codecvt_utf16
STD：：编解码器[医]utf 16
| Defined in header | | |
|---|
| template< class Elem, unsigned long Maxcode = 0x10ffff, std::codecvt_mode Mode = (std::codecvt_mode)0 > class codecvt_utf16 : public std::codecvt<Elem, char, std::mbstate_t>;; | | (since C++11) (deprecated in C++17) |
std::codecvt_utf16是std::codecvt方面，它封装Utf-16编码字节字符串与UC 2或UC 4字符串%28之间的转换，具体取决于Elem29%。此编解码面可用于二进制模式下读取和写入UTF-16文件。
模板参数
| Elem | - | either char16_t, char32_t, or wchar_t |
|---|
| Maxcode | - | the largest value of Elem that this facet will read or write without error |
| Mode | - | a constant of type std::codecvt_mode |
成员函数
| (constructor) | constructs a new codecvt_utf16 facet (public member function) |
|---|
| (destructor) | destroys a codecvt_utf16 facet (public member function) |
STD：：编解码器[医]utf 16：：codecvt[医]utf 16
| explicit codecvt_utf16( std::size_t refs = 0 | | |
|---|
构造一个新的std::codecvt_utf16方面，传递初始参考计数器。refs给基类。
参数
| refs | - | the number of references that link to the facet |
|---|
STD：：编解码器[医]utf 16：：~codecvt[医]utf 16
摧毁了这个面。与地区管理的方面不同，这个方面%27 s析构函数是公共的。
继承自STD：：编解码器
成员类型
| Member type | Definition |
|---|
| intern_type | internT |
| extern_type | externT |
| state_type | stateT |
成员对象
| Member name | Type |
|---|
| id (static) | std::locale::id |
成员函数
| out | invokes do_out (public member function of std::codecvt) |
|---|
| in | invokes do_in (public member function of std::codecvt) |
| unshift | invokes do_unshift (public member function of std::codecvt) |
| encoding | invokes do_encoding (public member function of std::codecvt) |
| always_noconv | invokes do_always_noconv (public member function of std::codecvt) |
| length | invokes do_length (public member function of std::codecvt) |
| max_length | invokes do_max_length (public member function of std::codecvt) |
受保护成员函数
| do_out virtual | converts a string from internT to externT, such as when writing to file (virtual protected member function of std::codecvt) |
|---|
| do_in virtual | converts a string from externT to internT, such as when reading from file (virtual protected member function of std::codecvt) |
| do_unshift virtual | generates the termination character sequence of externT characters for incomplete conversion (virtual protected member function of std::codecvt) |
| do_encoding virtual | returns the number of externT characters necessary to produce one internT character, if constant (virtual protected member function of std::codecvt) |
| do_always_noconv virtual | tests if the facet encodes an identity conversion for all valid argument values (virtual protected member function of std::codecvt) |
| do_length virtual | calculates the length of the externT string that would be consumed by conversion into given internT buffer (virtual protected member function of std::codecvt) |
| do_max_length virtual | returns the maximum number of externT characters that could be converted into a single internT character (virtual protected member function of std::codecvt) |
继承自STD：：编解码器[医]底座
| Member type | Definition |
|---|
| enum result { ok, partial, error, noconv }; | Unscoped enumeration type |
| Enumeration constant | Definition |
|---|
| ok | conversion was completed with no error |
| partial | not all source characters were converted |
| error | encountered an invalid character |
| noconv | no conversion required, input and output types are the same |
例
下面的示例演示32位系统上utf-16 le文件的解码。wchar_t...在一个16位的系统上wchar_t，第三个字符的解码将失败，因为std::codecvt_utf16<char16_t>生产UCS 2，而不是UTF-16。
二次
#include <fstream>
#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
void prepare_file()
{
// UTF-16le data (if host system is little-endian)
char16_t utf16le[4] ={0x007a, // latin small letter 'z' U+007a
0x6c34, // CJK ideograph "water" U+6c34
0xd834, 0xdd0b}; // musical sign segno U+1d10b
// store in a file
std::ofstream fout("text.txt"
fout.write( reinterpret_cast<char*>(utf16le), sizeof utf16le
}
int main()
{
prepare_file(
// open as a byte stream
std::wifstream fin("text.txt", std::ios::binary
// apply facet
fin.imbue(std::locale(fin.getloc(),
new std::codecvt_utf16<wchar_t, 0x10ffff, std::little_endian>)
for (wchar_t c; fin.get(c )
std::cout << std::showbase << std::hex << c << '\n';
}
二次
产出：
二次
二次
另见
| Characterconversions | locale-defined multibyte(UTF-8, GB18030) | UTF-8 | UTF-16 |
|---|
| UTF-16 | mbrtoc16 / c16rtomb(with C11's DR488) | codecvt<char16_t, char, mbstate_t>codecvt_utf8_utf16<char16_t>codecvt_utf8_utf16<char32_t>codecvt_utf8_utf16<wchar_t> | N/A |
| UCS2 | c16rtomb(without C11's DR488) | codecvt_utf8<char16_t> codecvt_utf8<wchar_t>(Windows). | codecvt_utf16<char16_t> codecvt_utf16<wchar_t>(Windows). |
| UTF-32 | mbrtoc32 / c32rtomb. | codecvt<char32_t, char, mbstate_t> codecvt_utf8<char32_t> codecvt_utf8<wchar_t>(non-Windows). | codecvt_utf16<char32_t> codecvt_utf16<wchar_t>(non-Windows). |
| system wide:UTF-32(non-Windows)UCS2(Windows) | mbsrtowcs / wcsrtombs use_facet<codecvt <wchar_t, char, mbstate_t>>(locale). | No | No |
| codecvt | converts between character encodings, including UTF-8, UTF-16, UTF-32 (class template) |
|---|
| codecvt_mode (C++11)(deprecated in C++17) | tags to alter behavior of the standard codecvt facets (enum) |
| codecvt_utf8 (C++11)(deprecated in C++17) | converts between UTF-8 and UCS2/UCS4 (class template) |
| codecvt_utf8_utf16 (C++11)(deprecated in C++17) | converts between UTF-8 and UTF-16 (class template) |
在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。
http：//en.cppreference.com/w/cpp/locale/codecvt[医]utf 16
