To implement a circular queue using a linked list, you will need to create a linked list with a fixed size and utilize two pointers: ‘front’ and ‘rear’.

A circular queue, often referred to as a ring buffer, is a linear data structure that adheres to the First-In-First-Out (FIFO) principle. It is termed “circular” because the last element in the queue points back to the first element, forming a circular link. When implementing this structure with a linked list, you will initialize a linked list of fixed size and maintain two pointers: the ‘front’ pointer, which references the first element in the queue, and the ‘rear’ pointer, which references the last element.

Initialization

Begin by setting both the ‘front’ and ‘rear’ pointers to ‘null’.

Enqueue Operation

When adding an element to the queue (the enqueue operation), first check if the queue is full. If it is not full, create a new node containing the data and append it to the rear of the queue. Update the ‘rear’ pointer to reference this new node. If the queue was previously empty, also update the ‘front’ pointer to point to this new node.

In cases where the queue is full, you have two options: either throw an overflow error or overwrite the oldest data in the queue.

Dequeue Operation

For removing an element from the queue (the dequeue operation), check if the queue is empty. If it is not empty, remove the node that the ‘front’ pointer is currently referencing and update the ‘front’ pointer to point to the next node in the queue. If this operation results in the last element being removed, also set the ‘rear’ pointer to ‘null’. If the queue is empty after the operation, you should throw an underflow error.

Checking Queue Status

To determine if the queue is full or empty, you can either maintain a count of the elements in the queue or rely on the ‘front’ and ‘rear’ pointers. The queue is considered empty if the ‘front’ pointer is ‘null’. Conversely, the queue is full if the next element of the ‘rear’ pointer is the ‘front’ pointer.

Conclusion

In summary, effectively managing the ‘front’ and ‘rear’ pointers is crucial when implementing a circular queue using a linked list. By doing so, you will ensure efficient addition and removal of elements from the queue.