std::codecvt::encoding
STD：：codecvt：：编码，做[医]编码
| Defined in header | | |
|---|---|---|
| public: int encoding() const; | (1) | |
| protected: virtual int do_encoding() const; | (2) | |
1%29公共成员函数，调用成员函数。do_encoding最派生的类。
2%29如果由此codecvt facet表示的编码将每个内部字符映射到相同的外部字符数，则返回该数字。如果编码是可变长度%28例如。UTF-8或UTF-16%29，返回0如果编码与状态相关，则返回-1...
返回值
的确切数目externT对应于一个字符的字符internT人物，如果是常量的话。0如果数字有变化，-1如果编码是状态依赖的。
非转换专业化std::codecvt<char, char,std::mbstate_t>回报1...
例外
| (none) | (until C++11) |
|---|---|
| noexcept specification: noexcept | (since C++11) |
例
二次
#include <locale>
#include <iostream>
int main()
{
std::cout << "en_US.utf8 is a variable-length encoding, encoding() returns "
<< std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
std::locale("en_US.utf8")
).encoding() << '\n';
std::cout << "zh_CN.gb18030 is also variable-length, encoding() == "
<< std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
std::locale("zh_CN.gb18030")
).encoding() << '\n';
std::cout << "ru_RU.koi8r is a single-byte encoding encoding() == "
<< std::use_facet<std::codecvt<wchar_t, char, std::mbstate_t>>(
std::locale("ru_RU.koi8r")
).encoding() << '\n';
}
二次
产出：
二次
en_US.utf8 is a variable-length encoding, encoding() returns 0
zh_CN.gb18030 is also variable-length, encoding() == 0
ru_RU.koi8r is a single-byte encoding encoding() == 1
二次
另见
| MB_CUR_MAX | maximum number of bytes in a multibyte character in the current C locale(macro variable) |
|---|---|
| do_max_length virtual | returns the maximum number of externT characters that could be converted into a single internT character (virtual protected member function) |
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