# What Is Queue in Data Structure W3schools?

//

Heather Bennett

In data structures, a queue is an abstract data type that follows the FIFO (First-In-First-Out) principle. It is similar to a real-life queue, where the person who arrives first gets served first. In programming, a queue allows you to store and retrieve elements in a specific order.

## Operations in Queue

A queue supports two main operations:

• Enqueue: This operation adds an element to the end of the queue.
• Dequeue: This operation removes the element from the front of the queue.

## Implementation of Queue

A queue can be implemented using various data structures such as arrays or linked lists. Here, we will discuss the implementation using an array:

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

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

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

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

// Other utility methods
}
```
```

In this implementation, we use an array called `this.items` to store the elements of the queue. The `enqueue()` method appends an element to the end of the array, while the `dequeue()` method removes and returns the first element from the array. The `isEmpty()` method checks if the queue is empty or not.

## Usage of Queue

The concept of queues finds its application in various real-life scenarios and computer algorithms. Some common use cases include:

• Process Scheduling: Operating systems often use queues to manage the execution of processes.
• Breadth-First Search: Queues are used in graph traversal algorithms like BFS to explore neighbors level by level.
• Print Spooling: When multiple print jobs are sent to a printer, they are placed in a queue and processed sequentially.

## Conclusion

A queue is a fundamental data structure that follows the FIFO principle. It allows efficient insertion and removal of elements in a specific order. Understanding queues and their implementation is crucial for building efficient algorithms and solving real-world problems.