map::key_type
A type that describes the sort key object that constitutes each element of the map.
typedef Key key_type;
Remarks
key_type is a synonym for the template parameter Key.
For more information on Key, see the Remarks section of the map Class topic.
Example
See example for value_type for an example of how to declare and use key_type.
Requirements
Header: <map>
Namespace: std