key_compare multiset_name.key_comp();

// C++ program to illustrate the
// multiset::key_comp() function
  
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    // Creating a multiset named m;
    multiset<int> m;
  
    multiset<int>::key_compare
        comp
        = m.key_comp();
  
    // Inserting elements into multiset
    m.insert(10);
    m.insert(20);
    m.insert(30);
    m.insert(40);
  
    cout << "Multiset has the elements\n";
  
    // Store key value of last element
    int highest = *m.rbegin();
  
    // initializing the iterator
    multiset<int>::iterator it = m.begin();
  
    // printing elements of all multiset
    do {
  
        cout << " " << *it;
  
    } while (comp(*it++, highest));
  
    return 0;
}

Multiset has the elements
 10 20 30 40

// C++ program to illustrate the
// multiset::key_comp() function
  
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    // Creating a multiset named m;
    multiset<int> m;
  
    multiset<int>::key_compare
        comp
        = m.key_comp();
  
    // Inserting elements into multiset
    m.insert(100);
    m.insert(200);
    m.insert(300);
    m.insert(400);
  
    cout << "Multiset has the elements\n";
  
    // Store key value of last element
    int highest = *m.rbegin();
  
    // initializing the iterator
    multiset<int>::iterator it = m.begin();
  
    // printing elements of all multiset
    do {
  
        cout << " " << *it;
  
    } while (comp(*it++, highest));
  
    return 0;
}

Multiset has the elements
 100 200 300 400