std::codecvt<InternT,ExternT,StateT>::encoding, do_encoding
From cppreference.com
| 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.
[edit] 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.
[edit] Example
Run this code
#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'; }
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
[edit] See also
| MB_CUR_MAX |
maximum number of bytes in a multibyte character in the current C locale (macro variable) |
| [virtual] |
returns the maximum number of ExternT characters that could be converted into a single InternT character (virtual protected member function) |
