<hash_set>
Defines the container template classes hash_set and hash_multiset and their supporting templates.
For a list of all members of this header, see <hash_set> Members.
#include <hash_set>
Remarks
In Visual C++ .NET 2003, members of the <hash_map> and <hash_set> header files are no longer in the std namespace, but rather have been moved into the stdext namespace. See The stdext Namespace for more information.