std::codecvt_utf16

Defined in header <codecvt>	?	?
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

~codecvt_utf16();	?	?

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

0x7a
0x6c34
0x1d10b

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)

 ? cppreference.com

在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。

http：//en.cppreference.com/w/cpp/locale/codecvt[医]utf 16

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最后更新于：2017-12-18