public member function
<unordered_set>
pair<iterator,iterator>
equal_range ( const key_type& k );
pair<const_iterator,const_iterator>
equal_range ( const key_type& k ) const;
Get range of elements with a specific key
Returns the bounds of a range that includes all the elements that compare equal to k. In unordered_set containers, where keys are unique, the range will include one element at most.
If k does not match any element in the container, the range returned has end as both its lower and upper range bounds.
All iterators in an unordered_set have const access to the elements (even those whose type is not prefixed with const_): Elements can be inserted or removed, but not modified while in the container.
Parameters
- k
- Value to be compared.
Member type key_type is the type of the elements in the container. In unordered_set containers it is the same as value_type, defined as an alias of the class's 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. Both may be aliases of the same iterator type.
Complexity
Average case: constant.
Worst case: linear in container size.
Iterator validity
No changes.