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

Defined in header `<locale>`
	(1)
public: int encoding() const throw();		(until C++11)
public: int encoding() const noexcept;		(since C++11)
	(2)
protected: virtual int do_encoding() const throw();		(until C++11)
protected: virtual int do_encoding() const noexcept;		(since C++11)

1) public member function, calls the member function do_encoding of the most derived class.

2) if the encoding represented by this codecvt facet maps each internal character to the same, constant number of external characters, returns that number. If the encoding is variable-length (e.g. UTF-8 or UTF-16), returns 0. If the encoding is state-dependent, returns -1.

Return value

The exact number of externT characters that correspond to one internT character, if constant. 0 if the number varies, -1 if the encoding is state-dependent.

The non-converting specialization std::codecvt<char, char, std::mbstate_t> returns 1.

Example

#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';
}

Output:

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

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)

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

Return value

Example

See also