has_facet

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

The template function returns true if a locale facet of class Facet is listed within the locale object loc.

In this implementation, you should write _HAS(loc, Facet) in place of has_facet(loc, (Facet *)0), because the second parameter is a nonstandard extension.