multiset empty() function in C++ STL

In this article we will be discussing the working, syntax and examples of multiset::empty() function in C++ STL.

What is a multiset in C++ STL?

Multisets are the containers similar to the set container, meaning they store the values in the form of keys same as a set, in a specific order.

In multiset the values are identified as keys as same as sets. The main difference between multiset and set is that the set has distinct keys, meaning no two keys are the same, in multiset there can be the same keys value.

Multiset keys are used to implement binary search trees.

What is multiset::empty()?

multiset::empty() function is an inbuilt function in C++ STL, which is defined in <set> header file.

This function checks if the associated multiset container is empty or not.

empty() checks the associated container size is 0 then will be true, else if any elements are present in the container or the size of the container is not 0 then the function will return false.

Syntax

ms_name.empty();

Parameters

The function accepts no parameter.

Return value

This function Boolean value true, if the container is empty else false.

Example

Input: std::multiset<int> mymultiset = {1, 2, 2, 3, 4};
   mymultiset.empty();
Output: false

Input: std::multiset<int> mymultiset;
   mymultiset.empty();
Output: true

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
int main() {
   int arr[] = {2, 3, 4, 5};
   multiset<int> check(arr, arr + 4);
   if (check.empty())
      cout <<"The multiset is empty";
   else
      cout << "The multiset isn't empty";
   return 0;
}

Output

If we run the above code it will generate the following output −

The multiset isn't empty

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
int main() {
   int arr[] = {};
   multiset<int> check(arr, arr + 0);
   if (check.empty())
      cout <<"The multiset is empty";
   else
      cout << "The multiset isn't empty";
   return 0;
}

Output

If we run the above code it will generate the following output −

The multiset is empty