What Is the Difference Between Enqueue and Dequeue in Data Structure?


Scott Campbell

When working with data structures, understanding the difference between enqueue and dequeue is fundamental. These two operations are commonly used in various data structures like queues and stacks. Let’s dive deeper into what enqueue and dequeue mean and how they differ from each other.


Enqueue is an operation that adds an element to the end of a queue or a similar data structure. In simple terms, it means inserting an item at the rear of the structure.

The enqueue operation follows a FIFO (First-In-First-Out) order, where the first element added will be the first one to be removed. This makes it suitable for scenarios where maintaining order is crucial.


Dequeue, on the other hand, removes an element from the front of a queue or a similar data structure. It essentially means deleting an item from the front of the structure.

The dequeue operation also follows a FIFO (First-In-First-Out) order, ensuring that elements are removed in the same order they were inserted.

Differences between Enqueue and Dequeue

  • Operation: Enqueue adds elements to the rear, while dequeue removes elements from the front.
  • Order: Both operations follow a FIFO order, which means that elements are processed in the same sequence they were inserted.
  • Purpose: Enqueue is used to add elements to a data structure, whereas dequeue is used to remove elements from it.
  • Data Structure: Enqueue and dequeue operations are commonly associated with queue-like structures such as queues and stacks.

Example: Enqueue and Dequeue

Let’s consider an example of a queue to better understand how enqueue and dequeue work:

Queue: [A, B, C]

Queue: [A, B, C, D]

Queue: [B, C, D]

In this example, we start with a queue containing three elements: A, B, and C. When we enqueue the element D, it gets added to the rear of the queue. On dequeuing an element from the front of the queue, A is removed.


In summary, enqueue and dequeue are essential operations when working with data structures like queues. Enqueue adds elements to the rear of a structure in a FIFO order, while dequeue removes elements from the front in the same order they were inserted. Understanding these operations is crucial for effectively implementing and utilizing various data structures.

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