Namespaces
Variants
Views
Actions

std::has_facet

From cppreference.com
< cpp‎ | locale
Revision as of 18:14, 26 August 2013 by P12 (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Defined in header <locale>
template< class Facet >
bool has_facet( const locale& loc );

Checks if the locale loc implements the facet Facet.

Contents

[edit] Parameters

loc - the locale object to query

[edit] Return value

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

[edit] Exceptions

(none) (until C++11)
noexcept specification:  
noexcept
  
(since C++11)

[edit] Example

#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

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