std::ctype_byname

template< class CharT >
class ctype_byname : public std::ctype<CharT>;

std::ctype_byname is a std::ctype facet which encapsulates character classification rules of the locale specified at its construction.

Specializations

The standard library is guaranteed to provide the following specializations:

Nested types

Member functions

explicit ctype_byname( const char* name, std::size_t refs = 0 );

explicit ctype_byname( const std::string& name, std::size_t refs = 0 );

protected:
~ctype_byname();

Notes

std::ctype_byname<char> was incorrectly declared as an explicit specialization in the synopsis of <locale>, and the declaration was removed by the resolution of LWG issue 1298, but it remains a required specialization, just like std::ctype_byname<wchar_t>.

Example

#include <iostream>
#include <locale>

int main()
{
    wchar_t c = L'\u00de'; // capital letter thorn
    
    std::locale loc("C");
    
    std::cout << "isupper('Þ', C locale) returned "
              << std::boolalpha << std::isupper(c, loc) << '\n';
    
    loc = std::locale(loc, new std::ctype_byname<wchar_t>("en_US.utf8"));
    
    std::cout << "isupper('Þ', C locale with Unicode ctype) returned "
              << std::boolalpha << std::isupper(c, loc) << '\n';
}

isupper('Þ', C locale) returned false
isupper('Þ', C locale with Unicode ctype) returned true

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also