C++ Queue

The C++ queue is a linear data structure that follows the First-In-First-Out (FIFO) principle, meaning the element that is added first will be the one to be removed first. C++ provides a convenient container adapter called std::queue in the Standard Library, which is implemented using other data structures, such as a deque (double-ended queue) by default.

Here’s how you can use std::queue in C++:

#include <iostream>
#include <queue>

int main() {
    std::queue<int> myQueue;

    // Enqueue elements
    myQueue.push(10);
    myQueue.push(20);
    myQueue.push(30);

    // Access the front element (the oldest element)
    std::cout << "Front element: " << myQueue.front() << std::endl;

    // Dequeue elements
    myQueue.pop();

    // Check if the queue is empty
    if (myQueue.empty()) {
        std::cout << "Queue is empty." << std::endl;
    } else {
        std::cout << "Queue is not empty." << std::endl;
    }

    // Get the size of the queue
    std::cout << "Queue size: " << myQueue.size() << std::endl;

    return 0;
}

In this example:

• We include the <queue> header to use std::queue.
• We create a queue called myQueue to store integer values.
• We use the push function to enqueue (add) elements to the queue.
• The front function allows us to access the front (oldest) element without removing it.
• We use the pop function to dequeue (remove) the front element.
• empty checks whether the queue is empty.
• size returns the number of elements in the queue.

std::queue provides a simple and convenient way to work with queues in C++. If you need more control or specific features, you can also implement a queue using other data structures like a linked list or an array.