C++ Standard Library, The: A Tutorial and Reference, 2nd Edition

7.8. Maps and Multimaps

Maps and multimaps are containers that manage key/value pairs as elements. These containers sort their elements automatically, according to a certain sorting criterion that is used for the key. The difference between the two is that multimaps allow duplicates, whereas maps do not (Figure 7.14).

Figure 7.14. Maps and Multimaps

To use a map or a multimap, you must include the header file <map>:

#include <map>

There, the types are defined as class templates inside namespace std:

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namespace std {    template <typename Key, typename T,              typename Compare = less<Key>,              typename ...