std::multimap<Key,T,Compare,Allocator>::equal_range

std::pair<iterator,iterator> equal_range( const Key& key );

std::pair<const_iterator,const_iterator> equal_range( const Key& key ) const;

template< class K >
std::pair<iterator,iterator> equal_range( const K& x );

template< class K >
std::pair<const_iterator,const_iterator> equal_range( const K& x ) const;

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. Alternatively, the first iterator may be obtained with lower_bound(), and the second with upper_bound().

Parameters

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.

Example

#include <iostream>
#include <map>
 
int main()
{
    std::multimap<int, char> dict {
        {1, 'A'},
        {2, 'B'},
        {2, 'C'},
        {2, 'D'},
        {4, 'E'},
        {3, 'F'}
    };
 
    auto range = dict.equal_range(2);
 
    for (auto i = range.first; i != range.second; ++i)
    {
        std::cout << i->first << ": " << i->second << '\n';
    }
}

2: B
2: C
2: D

See also