How to Check if a List is Empty in C++?

In C++, a list is a sequence container that allows non-contiguous memory allocation and is implemented using a doubly linked list. In this article, we will learn how to check if a list is empty in C++.

Example:

Input: 
myList = {1, 2, 3};

Output:
List is not empty.

Check if a List is Empty in C++

To check if a std::list is empty or not, we can use the std::list::empty() function that returns true if the list is empty and returns false if the list is not empty.

C++ Program to Check if a List is Empty

The below example demonstrates how we can use the empty() function to check if the given list is empty or not in C++ STL.

C++

// C++ Program to illustrate how to check if a list is empty
#include <iostream>
#include <list>
using namespace std;

int main()
{
    // Initialize a list
    list<int> myList = { 1, 2, 3 };

    // Check if the list is empty
    bool isEmpty = myList.empty();

    // Print the result
    if (isEmpty) {
        cout << "List is empty" << endl;
    }
    else {
        cout << "List is not empty" << endl;
    }

    return 0;
}

Output

List is not empty

Time Complexity: O(1)
Auxiliary Space: O(1)

Note: We can also use std::list::size() function to check if the given list is empty or not in C++.