What Is Enqueue in Data Structure?


Heather Bennett

What Is Enqueue in Data Structure?

Data structures are essential in computer programming as they provide a way to organize and store data efficiently. One commonly used data structure is a queue.

In a queue, elements are added at one end and removed from the other end. The process of adding elements to a queue is called enqueueing, and in this article, we will explore what enqueueing entails and how it is implemented.

Enqueueing Elements in a Queue

When enqueueing an element, it is placed at the end of the queue, also known as the rear or tail. This ensures that the element will be processed after all the previously added elements.

The enqueue operation typically follows the FIFO (First-In-First-Out) principle, meaning that the first element added will be the first one to be removed.

To illustrate this concept further, let’s consider an example of a queue representing a line of people waiting for a movie ticket. As new people arrive, they join the line at the back (enqueue), and when tickets become available, customers are served from the front (dequeue).

This ensures fairness by serving those who have been waiting the longest.

The Enqueue Process

The enqueue process involves two main steps:

  1. Create space: Before adding an element to the queue, we need to ensure that there is enough space to accommodate it. If the queue is implemented using an array with a fixed size, this may involve resizing or shifting existing elements.
  2. Add element: Once space is available, we can add the new element to the rear of the queue. This can be done by updating a pointer or index variable that keeps track of the end of the queue and assigning the new element to that position.

Let’s take a look at a simple implementation of enqueueing in Python using a list:

queue = []

def enqueue(element):


print(queue)  # Output: [5, 10, 15]

In this example, we have an empty list representing our queue. The enqueue() function takes an element as an argument and appends it to the end of the list using the append() method.

This ensures that new elements are always added to the rear of the queue.


Enqueueing is an essential operation in data structures, particularly in queues. It involves adding elements to the rear or tail of the queue, following the FIFO principle.

The process requires creating space for new elements and updating pointers or indices accordingly. Understanding how enqueueing works is crucial for effectively utilizing queues in various applications.

By incorporating enqueueing into your programming repertoire, you can handle data in a structured and organized manner, ensuring efficient processing and retrieval when needed.

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