How to Dequeue an Element from a Queue in C++?

How to Enqueue an Element into a Queue in C++?

Last Updated : 04 Mar, 2024

In C++ STL, we have a queue container that simulates the queue data structure and follows the FIFO (First In, First Out) rule. In this article, we will learn how to enqueue (insert) an element into a queue in C++.

Example:

Input: 
myQueue = {10, 20, 30};
elementToEnqueue= 40

Output: 
Queue after enqueue: 10 20 30 40

Add an Element to a Queue in C++

To enqueue an element into a std::queue in C++ STL, we can use the std::queue::push() function that inserts a new element at the end of the queue, after its current last element.

C++ Program to Enqueue an Element into a Queue

The below example demonstrates how we can enqueue an element into a queue in C++.

// C++ program to illustrate how to enqueue an element into
// a queue
#include <iostream>
#include <queue>
using namespace std;

int main()
{

    // Creating a queue of integers
    queue<int> myQueue;
    myQueue.push(10);
    myQueue.push(20);
    myQueue.push(30);

    // enqueue an element in a queue
    int elementToEnqueue = 40;
    myQueue.push(elementToEnqueue);

    // Displaying the queue elements
    cout << "Elements in a Queue are:" << endl;
    while (!myQueue.empty()) {
        cout << myQueue.front() << " ";
        myQueue.pop();
    }
    cout << endl;

    return 0;
}

Output

Elements in a Queue are:
10 20 30 40

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

How to Dequeue an Element from a Queue in C++?

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