Step 4: If Rear = Maxsize - 1 & Front != 0 (rear pointer is at the end of the queue and front is not at 0th index), then set Rear = 0.

Step 3: Check if the queue is empty, and set both Front and Rear to 0.

Step 2: If the queue is full, there will be an Overflow error.

Step 1: Check if the queue is full (Rear + 1 % Maxsize = Front).

You should follow the following steps to insert (enqueue) a data element into a circular queue. Here, you will deal with steps to implement queue operations: 1. These functions do not depend on the number of elements inside the queue or its size that is why these operations take constant execution time, i.e., O(1). Similarly, the tail node of a linked list can be connected to its head node by adding the address value of a head node in the reference field of the tail node.Įnqueue() and Dequeue() are the primary operations of the queue, which allow you to manipulate the data flow. Rear = (Rear + 1)% MaxSize = 0 (Reached loc. There is one empty space at the beginning of a queue, which means that the front pointer is pointing to location 1. Let’s say the MaxSize of your queue is 5, and the rear pointer has already reached the end of a queue. Now you will understand how you can achieve circular incrementation, with the help of an example. The circular incrementation is achievable with the help of the modulo division. That is, when you reach the end of a queue, you start from the beginning of a queue. Additionally, this queue works by the process of circular incrementation. However, implementing a circular link is a new addition that you need to execute. You can implement the circular queue using both the 1-D array and the Linked list. Representation of Circular Queue using Arrays and a Linked List

This operation takes place from the front of the Queue. deQueue() - Used to delete a value from the Circular Queue.

This operation takes place from the end of the Queue. enQueue(value) - Used to insert a new value in the Circular Queue.Rear - Used to get the end element of the Circular Queue.Front - Used to get the starting element of the Circular Queue.The Circular Queue is similar to a Linear Queue in the sense that it follows the FIFO (First In First Out) principle but differs in the fact that the last position is connected to the first position, replicating a circle. Hence, it is also called a Ring Buffer.Īs shown in the illustration above, the circular queue resolves the memory wastage problem with the help of a circular link. What is Circular Queue in a Data Structure?Ī circular queue is an extended version of a linear queue as it follows the First In First Out principle with the exception that it connects the last node of a queue to its first by forming a circular link. Thus, this particular type of queue is considered the best version of a queue data structure. This simple addition of a circular link resolves the problem of memory wastage in the case of queue implementation. Hence, experts introduced the concept of the circular queue to overcome this limitation.Īs shown in the figure above, the rear pointer arrives at the beginning of a queue with the help of a circular link to re-utilize the empty space to insert a new element. In the case of a linear queue, when the rear pointer reaches the MaxSize of a queue, there might be a possibility that after a certain number of dequeue() operations, it will create an empty space at the start of a queue.Īdditionally, this newly created empty space can never be re-utilized as the rear pointer reaches the end of a queue. However, memory is a crucial resource that you should always protect by analyzing all the implications while designing algorithms or solutions. Implementation of a linear queue brings the drawback of memory wastage. Why Was the Concept of Circular Queue Introduced? In this tutorial, you will explore a circular queue in a data structure along with its implementation and applications. You use a circular queue as a buffer to store the processes in order of their insertion and then remove them at the time of resource allocation or execution. It is used to manage the execution of computing processes or programs. It is common to use circular queues in a data structure in operating systems.

Java stack vs deque