size_type count( const Key& key ) const;
(1) (since C++11)

Returns the number of elements with key that compares equal to the specified argument key.


key - key value of the elements to count

Return value

Number of elements with key key.


linear in the number of elements with key key on average, worst case linear in the size of the container.

See also

finds element with specific key
(public member function)
returns range of elements matching a specific key
(public member function)