unordered_multimap size() function in C++ STL returns the number of elements in the unordered map.
Algorithm
Begin Declare an empty map container m. Performing reserve function to restrict the most appropriate bucket_count of the map container. Insert values in the map container. Print the size of the unorderd multimap container by using the size() function. End
Example Code
#include<iostream>
#include <bits/stdc++.h>
using namespace std;
int main() {
unordered_map<char, int> m; // declaring m as empty map container
m.reserve(6); //restricting the most appropriate bucket_count of map container
m.insert (pair<char, int>('b', 10)); // inserting some values
m.insert (pair<char, int>('a', 20));
cout << "The size is: " << m.size(); //printing the size of unordered multimap container by size() function.
return 0;
}Output
The size is :2