std::has_facet (3) - Linux Man Pages

std::has_facet: std::has_facet

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


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