template <class Facet> const Facet& use_facet(const locale& loc);
Requires:
Facet
is a facet class whose definition contains the public static member
id
as defined in [locale.facet].
Returns:
A reference to the corresponding facet of loc, if present.
Throws:
bad_cast
if
has_facet<Facet>(loc)
is
false.
Remarks:
The reference returned remains valid at least as long as any copy of
loc exists.
template <class Facet> bool has_facet(const locale& loc) noexcept;
Returns:
true if the facet requested is present in loc; otherwise false.