<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.
See Also
Reference
Thread Safety in the Standard C++ Library