Is Queue an ADT in Data Structure?


Angela Bailey

Is Queue an ADT in Data Structure?

A queue is a fundamental data structure in computer science that follows the First-In-First-Out (FIFO) principle. It is commonly used to store and process elements in an ordered manner, similar to a real-world queue of people waiting in line.

Abstract Data Type (ADT)

An Abstract Data Type (ADT) refers to a conceptual model that defines the behavior and properties of a data type, without specifying its implementation details. In simpler terms, it provides a high-level description of how operations can be performed on the data type, without going into the specifics of how those operations are actually implemented.

Queue as an ADT

Queue is indeed considered an Abstract Data Type in data structures. It is defined by a set of operations that can be performed on it, including:

  • enqueue(element): Adds an element to the end of the queue.
  • dequeue(): Removes and returns the element at the front of the queue.
  • isEmpty(): Checks if the queue is empty or not.
  • size(): Returns the number of elements currently present in the queue.
  • front(): Returns the element at the front of the queue without removing it.

In addition to these basic operations, there may be other specialized operations specific to certain implementations of queues, such as:

  • Circular Queue: A circular queue allows elements to be added at one end and removed from another end, forming a circular structure. This allows efficient utilization of memory.
  • Priority Queue: A priority queue assigns a priority value to each element and removes elements based on their priority rather than their arrival order.

Implementations of Queue

There are different ways to implement a queue, such as using arrays or linked lists. Each implementation has its own advantages and disadvantages, depending on the specific requirements of the application.

Array-based Implementation:

An array-based implementation of a queue uses a fixed-size array to store the elements. It maintains two pointers, one for the front and one for the rear of the queue, enabling efficient enqueue and dequeue operations. However, this approach may face limitations in terms of resizing and memory management.

Linked List Implementation:

A linked list-based implementation uses nodes that are dynamically allocated in memory and connected via pointers. This allows for dynamic size adjustments and efficient enqueue and dequeue operations. However, it may result in additional memory overhead due to node allocation.


In summary, a queue is considered an Abstract Data Type (ADT) in data structures. It provides a high-level description of how elements can be added, removed, and accessed in an ordered manner. The specific implementation details can vary based on requirements and constraints of the application at hand.

By understanding queues as an ADT, developers can leverage its properties to efficiently solve various real-world problems that require processing elements in a specific order.

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