std::has_facet

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Defined in header `<locale>`

template< class Facet > bool has_facet( const locale& loc );

Checks if the locale loc implements the facet Facet.

#include <iostream>
#include <locale>
// minimal custom facet
struct myfacet : public std::locale::facet {
    static std::locale::id id;
};
std::locale::id myfacet::id;
int main()
{
    // loc is a "C" locale with myfacet added
    std::locale loc(std::locale::classic(), new myfacet);
    std::cout << std::boolalpha
              << "Can loc classify chars? "
              << std::has_facet<std::ctype<char>>(loc) << '\n'
              << "Can loc classify char32_t? "
              << std::has_facet<std::ctype<char32_t>>(loc) << '\n'
              << "Does loc implement myfacet? "
              << std::has_facet<myfacet>(loc) << '\n';
}

Output:

Can loc classify chars? true
Can loc classify char32_t? false
Does loc implement myfacet? true

[edit] See also

locale

set of polymorphic facets that encapsulate cultural differences
(class)

use_facet

obtains a facet from a locale
(function template)

std::has_facet

From Cppreference

Contents

[edit] Parameters

[edit] Return value

[edit] Exception specification

[edit] Example

[edit] See also