The Waite Group's C++ Primer Plus, Third Edition

Additional Members for Sets and Maps

Associative containers, of which sets and maps are models, have a Key template parameter and a Compare template parameter indicating, respectively, the type of the key used to order the contents and the function object, termed a comparison object, used to compare key values. For the set and multiset containers, the stored keys are the stored values, so the key type is the same as the value type. For the map and multimap containers, the stored values of one type (template parameter T) are associated with a key type (template parameter Key), and the value type is pair<const Key, T>. Associative containers introduce additional members to describe these features, as listed in Table G.6.

Table G.6. Types defined ...