What Is Enqueue Operation in Data Structure?


Scott Campbell

The enqueue operation is a fundamental concept in data structures. It refers to the process of adding an element to the end of a queue. In this article, we will explore what enqueue operation is, how it works, and its significance in various applications.

Understanding Enqueue Operation

In simple terms, enqueue operation adds an element to the rear or end of a queue. A queue follows the First-In-First-Out (FIFO) principle, meaning that the element added first will be the first one to be removed. Think of it as a line of people waiting for something – the person who joins the line last will have to wait for everyone else to be served before their turn comes.

To perform an enqueue operation, you need access to both ends of the queue – front and rear. The new element is inserted at the rear end, also known as tail or back. If the queue is empty initially, both front and rear would point to the newly added element.

Enqueue Operation Steps:

  1. Create a new node or allocate memory for the new element.
  2. Assign a value to the new node or element.
  3. If the queue is empty, set both front and rear pointers to this new node.
  4. If it’s not empty, update only the rear pointer to point at this new node.
  5. Increment the count variable (if used) tracking the number of elements in the queue.

It’s important to note that enqueue operation can fail if there is no more memory available for allocating a new node or if there are limitations due to hardware constraints. Proper error handling should be implemented in such cases.

Applications of Enqueue Operation

The enqueue operation is widely used in computer science and everyday scenarios. Here are a few examples:

1. Queues

As mentioned earlier, enqueue operation plays a crucial role in implementing queues. Queues are used in various algorithms and data structures, such as breadth-first search, job scheduling, printer spooling, and more.

2. Message Queues

In message-oriented middleware systems, enqueue operation is used to add messages to a queue for processing or delivery. This allows for asynchronous communication between different components or services.

3. Event Handling

In graphical user interfaces (GUIs) and event-driven programming, enqueue operation is utilized to add events to an event queue. These events can then be processed one by one in the order they were added.


The enqueue operation is a fundamental concept in data structures that allows us to add elements to the end of a queue. Understanding how it works and its significance in various applications is vital for developing efficient algorithms and systems.

By properly implementing the enqueue operation and leveraging its capabilities, we can create powerful solutions that meet the needs of different domains. So next time you come across a problem where you need to maintain order or process elements sequentially, consider using the enqueue operation!

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