映射和多重映射基于某一类型Key的键集的存在，提供对T类型的数据进行快速和高效的检索。对map而言，键只是指存储在容器中的某一成员。Map不支持副本键，multimap支持副本键。-Mapping and multiple mapping based on a key set of type Key exist, provide fast and efficient retrieval of data of type T. On the map, the key is only stored in the container of a member of. Map does not support the copy of the key, multimap support the copy of the key.