std::codecvt

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C++
 
本地化库
语言环境方面
Original:
Locales and facets
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locale
字符分类
Original:
Character classification
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转换
Original:
Conversions
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wstring_convert（C++11）
wbuffer_convert（C++11）
小面类的基类
Original:
Facet category base classes
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小面类
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Facet categories
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特定于语言环境的方面
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Locale-specific facets
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代码转换方面
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Code conversion facets
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codecvt_utf8（C++11）
codecvt_utf16（C++11）
codecvt_utf8_utf16（C++11）
codecvt_mode（C++11）
C语言环境
Original:
C locale
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std::codecvt
 
Defined in header <locale>
template<

    class InternT,
    class ExternT,
    class State

> class codecvt;
类std::codecvt封装转换的字符串，其中包括广泛和多，从一种编码转换到另一个。所有文件I / O操作通过std::basic_fstream<CharT>使用的语言环境充满流中的std::codecvt<CharT, char, std::mbstate_t>方面.
Original:
Class std::codecvt encapsulates conversion of character strings, including wide and multibyte, from one encoding to another. All file I/O operations performed through std::basic_fstream<CharT> use the std::codecvt<CharT, char, std::mbstate_t> facet of the locale imbued in the stream.
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cpp/locale/codecvt basecpp/locale/locale/facetstd-codecvt-inheritance.svg
关于这幅图像

Inheritance diagram

四个专业所提供的标准库和所有语言环境中创建的对象在C + +程序实现
Original:
Four specializations are provided by the standard library and are implemented by all locale objects created in a C++ program:
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Defined in header <locale>
std::codecvt<char, char, std::mbstate_t>
身份的转换
Original:
identity conversion
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std::codecvt<char16_t, char, std::mbstate_t>
UTF-16和UTF-8之间的转换（C++11 起）
Original:
conversion between UTF-16 and UTF-8 （C++11 起）
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std::codecvt<char32_t, char, std::mbstate_t>
UTF-32和UTF-8（C++11 起）之间的转换
Original:
conversion between UTF-32 and UTF-8 （C++11 起）
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std::codecvt<wchar_t, char, std::mbstate_t>
区域设置特定的宽字符串和狭窄的，可能是多字节字符串之间的转换
Original:
locale-specific conversion between wide string and narrow, possibly multibyte, string
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目录

[编辑] 会员类型

会员类型
Original:
Member type
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 Definition
intern_type internT
extern_type externT
state_type stateT

[编辑] 会员对象

会员名称
Original:
Member name
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 Type
id （静态的） std::locale::id

[编辑] 成员函数
构造一个新codecvt方面
Original:
constructs a new codecvt facet
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（公共成员函数）
解构一个codecvt方面
Original:
destructs a codecvt facet
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（受保护的成员函数）
调用do_out
Original:
invokes do_out
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（公共成员函数） [edit]
调用do_in
Original:
invokes do_in
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（公共成员函数） [edit]
调用do_unshift
Original:
invokes do_unshift
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（公共成员函数） [edit]
调用do_encoding
Original:
invokes do_encoding
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（公共成员函数） [edit]
调用do_always_noconv
Original:
invokes do_always_noconv
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（公共成员函数） [edit]
调用do_length
Original:
invokes do_length
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（公共成员函数） [edit]
调用do_max_length
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invokes do_max_length
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（公共成员函数） [edit]

[编辑] 受保护的成员函数

[虚拟的] </ SPAN></div></div>
转换成一个字符串，如写入文件时，从Internt的externT
Original:
converts a string from internT to externT, such as when writing to file
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
将字符串转换，如从文件读取时，从externT到Internt的
Original:
converts a string from externT to internT, such as when reading from file
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
产生的externT不完全转化为字符序列终止符
Original:
generates the termination character sequence of externT characters for incomplete conversion
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
返回的externT需要产生一个Internt的字符的字符数，如果不变
Original:
returns the number of externT characters necessary to produce one internT character, if constant
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
该方面的测试，如果所有有效参数值的标识转换为编码
Original:
tests if the facet encodes an identity conversion for all valid argument values
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
计算将转换成给定的Internt的缓冲区消耗的externT字符串，该字符串的长度
Original:
calculates the length of the externT string that would be consumed by conversion into given internT buffer
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（虚拟保护成员函数） [edit]
[虚拟的] </ SPAN></div></div>
返回的最大数目，可以被转换成一个单一的Internt的字符externT字符
Original:
returns the maximum number of externT characters that could be converted into a single internT character
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（虚拟保护成员函数） [edit]

Inherited from std::codecvt_base

会员类型
Original:
Member type
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 Definition
enum result { ok, partial, error, noconv };
无作用域的枚举类型
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Unscoped enumeration type
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枚举常量
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Enumeration constant
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 Definition
ok
转换完成，没有错误
Original:
conversion was completed with no error
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partial
不是所有的源字符被转换了
Original:
not all source characters were converted
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error
遇到无效的字符
Original:
encountered an invalid character
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noconv
没有转换，输入和输出类型是相同的
Original:
no conversion required, input and output types are the same
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[编辑] 为例

下面的示例读取一个UTF-8文件使用的语言环境，实现了UTF-8转换codecvt <wchar_t, char, mbstate_t>
Original:
The following examples reads a UTF-8 file using a locale which implements UTF-8 conversion in codecvt<wchar_t, char, mbstate_t>
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#include <iostream>
#include <fstream>
#include <string>
#include <locale>
#include <iomanip>
int main()
{
    // UTF-8 narrow multibyte encoding
    std::ofstream("text.txt") << u8"z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋"
                                           // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b";
    std::wifstream fin("text.txt");
    fin.imbue(std::locale("en_US.UTF-8")); // this locale's codecvt<wchar_t, char, mbstate_t>
                                           // converts UTF-8 to UCS4
    std::cout << "The UTF-8 file contains the following wide characters: \n";
    for(wchar_t c; fin >> c; )
        std::cout << "U+" << std::hex << std::setw(4) << std::setfill('0') << c << '\n';
}

Output: 

The UTF-8 file contains the following wide characters:
U+007a
U+00df
U+6c34
U+1d10b

[编辑] 另请参阅

Character
conversions 		narrow multibyte
(char) 		UTF-8
(char) 		UTF-16
(char16_t)
UTF-16 mbrtoc16 / c16rtomb codecvt<char16_t, char, mbstate_t>
codecvt_utf8_utf16<char16_t>
codecvt_utf8_utf16<char32_t>
codecvt_utf8_utf16<wchar_t> 		N/A
UCS2 No codecvt_utf8<char16_t> codecvt_utf16<char16_t>
UTF-32/UCS4
(char32_t) 		mbrtoc32 / c32rtomb codecvt<char32_t, char, mbstate_t>
codecvt_utf8<char32_t> 		codecvt_utf16<char32_t>
UCS2/UCS4
(wchar_t) 		No codecvt_utf8<wchar_t> codecvt_utf16<wchar_t>
wide
(wchar_t) 		codecvt<wchar_t, char, mbstate_t>
mbsrtowcs / wcsrtombs 		No No
定义字符转换错误
Original:
defines character conversion errors
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（类模板）
创建名为locale的一个codecvt方面的
Original:
creates a codecvt facet for the named locale
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（类模板）
（C++11）
之间的转换UTF-8和UCS2/UCS4
Original:
converts between UTF-8 and UCS2/UCS4
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（类模板） [edit]
（C++11）
之间的转换UTF-16和UCS2/UCS4
Original:
converts between UTF-16 and UCS2/UCS4
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（类模板） [edit]
（C++11）
 converts between UTF-8 and UTF-16
（类模板） [edit]

来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/locale/codecvt&oldid=28480”