Queue

Introduction:

In the world of computer science, data structures play a crucial role in organizing and managing information efficiently. One such fundamental data structure is the queue. In this article, we will explore the concept of queues, understand their significance, and delve into how they are used in various programming languages, including C#, JavaScript, Python, and PHP. Get ready to enhance your understanding of queues and their practical applications!

Understanding Queues:

A queue is a collection that follows the principle of “first in, first out” (FIFO). It resembles a real-life queue, like the line of people waiting for a movie ticket. The entities in a queue are kept in order, and the primary operations performed on a queue are enqueue (adding entities to the rear terminal position) and dequeue (removing entities from the front terminal position).

Queues in Real-World Applications:

Queues find applications in various real-world scenarios. For example, consider a messaging application where messages are sent and received. The messages are stored in a queue, ensuring that they are processed in the order they arrive. Similarly, in operating systems, queues are used to manage processes, ensuring fairness and efficient resource allocation.
Implementing Queues in Programming Languages:

Links

Code Examples

C#
using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        Queue<string> myQueue = new Queue<string>();

        myQueue.Enqueue("First");
        myQueue.Enqueue("Second");
        myQueue.Enqueue("Third");

        while (myQueue.Count > 0)
        {
            string item = myQueue.Dequeue();
            Console.WriteLine(item);
        }
    }
}

JavaScript
class Queue {
    constructor() {
        this.items = [];
    }

    enqueue(element) {
        this.items.push(element);
    }

    dequeue() {
        if (this.isEmpty()) {
            return "Underflow";
        }
        return this.items.shift();
    }

    isEmpty() {
        return this.items.length === 0;
    }
}

const myQueue = new Queue();
myQueue.enqueue("First");
myQueue.enqueue("Second");
myQueue.enqueue("Third");

while (!myQueue.isEmpty()) {
    console.log(myQueue.dequeue());
}

Python
class Queue:
    def __init__(self):
        self.items = []

    def enqueue(self, item):
        self.items.append(item)

    def dequeue(self):
        if self.is_empty():
            return "Underflow"
        return self.items.pop(0)

    def is_empty(self):
        return len(self.items) == 0

my_queue = Queue()
my_queue.enqueue("First")
my_queue.enqueue("Second")
my_queue.enqueue("Third")

while not my_queue.is_empty():
    print(my_queue.dequeue())

PHP
class Queue {
    protected $queue = [];

    public function enqueue($item) {
        array_push($this->queue, $item);
    }

    public function dequeue() {
        if ($this->isEmpty()) {
            return "Underflow";
        }
        return array_shift($this->queue);
    }

    public function isEmpty() {
        return empty($this->queue);
    }
}

$myQueue = new Queue();
$myQueue->enqueue("First");
$myQueue->enqueue("Second");
$myQueue->enqueue("Third");

while (!$myQueue->isEmpty()) {
    echo $myQueue->dequeue() . "/n";
}

Conclusion