What Is Peek in Queue Data Structure?


Larry Thompson

The peek operation is an important feature of the queue data structure. In this article, we will explore what peek is and how it can be used to access elements in a queue.

What is a Queue?

A queue is a linear data structure that follows the FIFO (First-In-First-Out) principle. It means that the element that is inserted first will be the first one to be removed from the queue. Think of it as a line of people waiting for their turn at a ticket counter or in a queue outside a restaurant.

The Peek Operation

The peek operation in a queue allows us to access the element at the front of the queue without removing it. This operation provides us with a way to examine what element will be dequeued next, without actually dequeuing it. It is similar to looking at the person standing at the front of the line without asking them to move aside.

To perform a peek operation, we can use the following steps:

  • Step 1: Check if the queue is empty. If it is, then there are no elements to peek.
  • Step 2: If the queue is not empty, return the element at the front of the queue without removing it.

The peek operation does not affect the state of the queue. The element remains in its original position, and other elements can still be enqueued or dequeued as usual.

Why Use Peek?

The peek operation can be useful in situations where we need to access but not modify or remove an element from a queue. Here are some scenarios where peek can come in handy:

  • 1. Priority Queue: In a priority queue, elements are stored based on their priority.

    Peek allows us to examine the element with the highest priority without changing the order.

  • 2. Scheduling: When scheduling tasks or processes, peek can help determine which task is next in line to be executed.
  • 3. Implementing Algorithms: Some algorithms require examining the next element in a queue without removing it, and peek provides a way to do that efficiently.


Let’s consider an example of a queue that stores integers: [10, 20, 30, 40, 50].

If we perform a peek operation on this queue, we will get the value 10, which is the element at the front of the queue. However, the actual queue remains unchanged.

The resulting queue after performing a peek operation will still be: [10, 20, 30, 40, 50].


The peek operation in a queue allows us to examine the element at the front of the queue without removing it. It is useful in various scenarios where accessing an element without modifying or removing it is required.

By using the peek operation, we can efficiently retrieve information from queues and make informed decisions based on it.

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