public member function


   equal_range ( const key_type& k );
   equal_range ( const key_type& k ) const;
Get range of elements with specific key
Returns the bounds of a range that includes all the elements in the container with a key that compares equal to k. In unordered_map containers, where keys are unique, the range will include one element at most.

If k does not match any key in the container, the range returned has end as both its lower and upper range bounds.


Key value to be compared.
Member type key_type is the type of the keys for the elements in the container, defined in unordered_map as an alias of its first template parameter (Key).

Return value

The function returns a pair, where its member pair::first is an iterator to the lower bound of the range, and pair::second is an iterator to its upper bound. The elements in the range are those between these two iterators, including pair::first, but not pair::second.

Member types iterator and const_iterator are forward iterator types.


See unordered_multimap::equal_range.


Average case: constant.
Worst case: linear in container size.

Iterator validity

No changes.

See also