The multimap::equal_range() is a built-in function in C++ STL which returns an iterator of pairs. The pair refers to the bounds of a range that includes all the elements in the container which have a key equivalent to k. If there are no matches with key K, the range returned is of length 0 with both iterators pointing to the first element that has a key considered to go after k according to the container’s internal comparison object (key_comp).
Syntax:
iterator multimap_name.equal_range(key)
Parameters: This function accepts a single mandatory parameter key which specifies the element whose range in the container is to be returned.
Return Value: The function returns an iterator of pairs. The pair refers to the bounds of a range that includes all the elements in the container which have a key equivalent to k. If there are no matches with key K, the range returned is of length 0 with both iterators pointing to the first element that has a key considered to go after k according to the container’s internal comparison object (key_comp).
Program below illustrate the above method:
C++
// C++ program to illustrate the// multimap::equal_range() function#include <bits/stdc++.h>using namespace std;int main(){ // initialize container multimap<int, int> mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 1, 20 }); mp.insert({ 5, 50 }); // Stores the range of key 1 auto it = mp.equal_range(1); cout << "The multimap elements of key 1 is : \n"; cout << "KEY\tELEMENT\n"; // Prints all the elements of key 1 for (auto itr = it.first; itr != it.second; ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } return 0;} |
The multimap elements of key 1 is : KEY ELEMENT 1 40 1 20
