< cpp‎ | locale‎ | locale
Defined in header <locale>
class locale::id;

The class std::locale::id provides implementation-specific identification of a locale facet. Each class derived from std::locale::facet must have a public static member named id of type std::locale::id and each std::locale object maintains a list of facets it implements, indexed by their ids.

Facets with the same id belong to the same facet category and replace each other when added to a locale object.

Member functions

constructs a new id
(public member function)
copy assignment operator is deleted
(public member function)


The following example shows how to construct a minimal custom facet.

#include <iostream>
#include <locale>
struct myfacet : std::locale::facet
    myfacet(std::size_t refs = 0) : facet(refs) {}
    static std::locale::id id;
std::locale::id myfacet::id;
int main()
    std::locale myloc(std::locale(), new myfacet);
    std::cout << "has_facet<myfacet>(myloc) returns " << std::boolalpha
              << std::has_facet<myfacet>(myloc) << '\n';


has_facet<myfacet>(myloc) returns true

See also

the base class for all facet categories: each facet of any category is derived from this type