std::codecvt<InternT,ExternT,StateT>:: encoding, do_encoding

返回值

对应一个 internT 字符所需的精确 externT 字符数量（若为常量值）。若该数值可变则为 ​ 0 ​ ，若编码具有状态依赖性则为 - 1 。

不进行转换的特化 std:: codecvt < char , char , std:: mbstate_t > 返回 1 。

示例

#include <iostream>
#include <locale>
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';
}

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

参见