How to Find the Size of a Deque in C++?

In C++, deque also known as double-ended queues are containers that allow efficient insertion and deletion operations from both ends of the deque. In this article, we will learn how to find the size of a deque in C++.

Example:

Input:
myDeque =  {10, 20, 30, 40, 50}

Output:
Size of the Deque is: 5

Find the Size of a Deque in C++

In C++, the std::deque container keeps track of its size. We can simply use the std::deque::size() member function of the std::deque class to get the size of the deque container. It returns the size i.e., the number of elements present in the deque in the form of an integer.

Syntax of std::deque::size()

dq_name.size() 

C++ Program to Find the Size of a Deque

The below program demonstrates how we can find the size of a deque in C++.

C++

// C++ Program to demonstrate how we can find the size of a
// deque
#include <deque>
#include <iostream>
using namespace std;

int main()
{
    // Initializing a deque
    deque<int> dq = { 10, 20, 30, 40, 50 };

    // Finding the size of the deque
    int dequeSize = dq.size();

    // Printing the size of the deque
    cout << "Size of the Deque is: " << dequeSize << endl;

    return 0;
}

Output

Size of the Deque is: 5

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