std::pair<iterator,iterator> equal_range( const Key& key );
(since C++11)
std::pair<const_iterator,const_iterator> equal_range( const Key& key ) const;
(since C++11)

Returns a range containing all elements with key key in the container. The range is defined by two iterators, the first pointing to the first element of the wanted range and the second pointing past the last element of the range.


key - key value to compare the elements to

Return value

std::pair containing a pair of iterators defining the wanted range. If there are no such elements, past-the-end (see end()) iterators are returned as both elements of the pair.


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


#include <iostream>
#include <unordered_map>
int main()
    std::unordered_map<int,char> map = {{1,'a'},{1,'b'},{1,'d'},{2,'b'}};
    auto range = map.equal_range(1);
    for (auto it = range.first; it != range.second; ++it) {
        std::cout << it->first << ' ' << it->second << '\n';


1 a

See also

finds element with specific key
(public member function)

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