std::set::equal_range

 

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std::pair<iterator,iterator> equal_range( const Key& key );	(1)
std::pair<const_iterator,const_iterator> equal_range( const Key& key ) const;	(2)
template< class K > std::pair<iterator,iterator> equal_range( const K& x );	(3)	(since C++14)
template< class K > std::pair<const_iterator,const_iterator> equal_range( const K& x ) const;	(4)	(since C++14)

Returns a range containing all elements with the given key in the container. The range is defined by two iterators, one pointing to the first element that is not less than key and another pointing to the first element greater than key. The first iterator may be alternatively obtained with lower_bound(), the second - with upper_bound().

1-2) Compares the keys to key.

3,4) Compares the keys to the value x. These templates only participate in overload resolution if the type Compare::is_transparent exists. They allow calling this function without constructing an instance of Key.

Parameters

key	-	key value to compare the elements to
x	-	alternative value that can be compared to Key

Return value

std::pair containing a pair of iterators defining the wanted range: the first pointing to the first element that is not less than key and the second pointing to the first element greater than key.

If there are no elements not less than key, past-the-end (see end()) iterator is returned as the first element. Similarly if there are no elements greater than key, past-the-end iterator is returned as the second element.

Complexity

Logarithmic in the size of the container.

See also

find	finds element with specific key (public member function)
upper_bound	returns an iterator to the first element greater than a certain value (public member function)
lower_bound	returns an iterator to the first element not less than the given value (public member function)