C++ multiset - key_comp() Function

The C++ multiset::key_comp function returns a copy of the comparison object used by the container. By default, it is a less object, which returns the same as operator<.

Syntax

C++98
C++11

key_compare key_comp() const;

key_compare key_comp() const;

Parameters

No parameter is required.

Return Value

The comparison object associated to the container.

Time Complexity

Constant i.e, Θ(1).

Example:

In the example below, the multiset::key_comp function is used print all elements in the given multiset which are less than 50.

#include <iostream>
#include <set>
using namespace std;
 
int main (){
  multiset<int> MSet{10, 20, 20, 30, 30, 40, 70, 80, 90};
  multiset<int>::iterator it;

  //printing the content of the multiset
  cout<<"MSet contains:";
  for(it = MSet.begin(); it != MSet.end(); ++it)
    cout<<" "<<*it;

  //creating a key_comp object
  multiset<int>::key_compare MyComp = MSet.key_comp();

  //printing all elements in multiset which are 
  //less than 50 using key_comp object
  it = MSet.begin();
  cout<<"\nElements less than 50 in MSet:\n";
  while(MyComp(*it, 50)){
    cout<<*it<<" ";
    it++;
  }

  return 0;
}

The output of the above code will be:

MSet contains: 10 20 20 30 30 40 70 80 90
Elements less than 50 in MSet:
10 20 20 30 30 40

❮ C++ <set> Library