NAME

std::has_facet - std::has_facet

Synopsis

Defined in header <locale>
template< class Facet > (until C++11)
bool has_facet( const locale& loc ) throw();
template< class Facet > (since C++11)
bool has_facet( const locale& loc ) noexcept;

Checks if the locale loc implements the facet Facet.

Parameters

loc - the locale object to query

Return value

Returns true if the facet Facet was installed in the locale loc, false otherwise.

Example

// Run this code

#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

See also

locale set of polymorphic facets that encapsulate cultural differences
(class)
use_facet obtains a facet from a locale
(function template)