What is a queue in C++ and how is it implemented?

Table of Contents

• Introduction
• Queue Operations
  • 1. Enqueue
  • 2. Dequeue
  • 3. Front
  • 4. Rear
  • 5. IsEmpty
• Implementation of a Queue in C++
  • Using Arrays
  • Using Linked Lists
• Conclusion

Introduction

A queue is a fundamental data structure that operates on a First In, First Out (FIFO) principle, where the first element added is the first one to be removed. Queues are widely used in various algorithms and applications, such as task scheduling and buffering. In C++, queues can be implemented using arrays, linked lists, or the standard library's std::queue. This guide provides an overview of queues and demonstrates practical implementations in C++.

Queue Operations

A queue supports several key operations:

1. Enqueue

Adds an element to the rear of the queue.

2. Dequeue

Removes an element from the front of the queue.

3. Front

Returns the element at the front of the queue without removing it.

4. Rear

Returns the element at the rear of the queue without removing it.

5. IsEmpty

Checks whether the queue is empty.

Implementation of a Queue in C++

Using Arrays

You can implement a queue using a static array with two indices to keep track of the front and rear positions.

Implementation Example:

Using Linked Lists

A queue can also be implemented using a singly linked list where each node contains data and pointers to the next node. The front pointer points to the head of the list, and the rear pointer points to the tail.

Implementation Example:

Conclusion

Queues in C++ can be implemented using arrays or linked lists, each with its advantages. Array-based queues are simple and efficient but have a fixed size, whereas linked-list-based queues offer dynamic sizing and flexibility but involve additional memory overhead. Understanding how to implement and use queues is essential for managing data and solving problems efficiently in C++.