The Standard Template Library (STL) provides only one type of associative container–the sorted associative container. The STL sorted associative containers are map, multimap, set, and multiset. However, there is another type of associative container: the hashed associative container. This container should really be in the Standard Template Library but isn’t there because it was proposed too late to be included in the ANSI/ISO Standard. The difference between a sorted associative container and a hashed associative container is that the former keeps the keys sorted according to some total order. For example, in a map