Check if MultiSet is Empty in C++

This tutorial will discuss how to check if multiset is empty in C++?.

Multiset in C++ provides a function called ’empty()’, which returns true if there are no elements in the multiset. For instance, if we create an empty multiset named ‘numSet’, it won’t contain any elements.

std::multiset<int> numSet;

When we call the ’empty()’ function on this multiset, it will return true.

// Check if multiset is empty
if(numSet.empty())
{
    std::cout<< "MultiSet is empty" << std::endl;
}
else
{
    std::cout<< "MultiSet is not empty" << std::endl;
}

Output:

MultiSet is empty

Now, if we insert two elements into ‘numSet’ using the ‘insert’ function, and subsequently call the ’empty’ function, it will return false. This is because ‘numSet’ now contains two elements.

numSet.insert(45);
numSet.insert(41);

// Check if multiset is empty
if(numSet.empty())
{
    std::cout<< "MultiSet is empty" << std::endl;
}
else
{
    std::cout<< "MultiSet is not empty" << std::endl;
}

Output:

MultiSet is not empty

Thus, we can use the ’empty’ member function of multiset to check whether a multiset is empty or not.

Let’s see the complete example,

#include <iostream>
#include <set>

int main()
{
    std::multiset<int> numSet;

    // Check if multiset is empty
    if(numSet.empty())
    {
        std::cout<< "MultiSet is empty" << std::endl;
    }
    else
    {
        std::cout<< "MultiSet is not empty" << std::endl;
    }

    // Insert two elements on multiset
    numSet.insert(45);
    numSet.insert(41);

    // Check if multiset is empty
    if(numSet.empty())
    {
        std::cout<< "MultiSet is empty" << std::endl;
    }
    else
    {
        std::cout<< "MultiSet is not empty" << std::endl;
    }

    return 0;
}

Output

MultiSet is empty
MultiSet is not empty

Summary

Today, we learned how to check if multiset is empty in C++?.