Implementation of Queue using Linked List in C++

Arrays have a fixed size, which means you need to define the maximum number of elements beforehand. If the array gets full, you either need to resize it (which is expensive) or stop inserting. On the other hand, a linked list is dynamic—it uses memory as needed. You can keep adding elements until system memory is available, making it more efficient and flexible for queue operations.

If we try to remove (dequeue) an element when the queue is already empty, it should not crash the program. Instead, the program should display a proper message like “Queue is empty. Cannot dequeue.” and skip the deletion process. In linked list implementation, this is handled by checking if the front pointer is NULL.

Yes, circular queues can also be implemented using linked lists. In a circular queue, after the last node, the next pointer links back to the first node. This structure is useful in scenarios like memory management, round-robin scheduling, or buffering, where the queue starts over again after reaching the end.

Yes. When we remove a node from the front of the queue, we also free the memory allocated to that node using the delete keyword in C++. This ensures we don’t waste memory or cause memory leaks. It’s one of the benefits of using dynamic memory allocation responsibly in linked lists.

Yes, both enqueue (insertion at rear) and dequeue (deletion at front) operations are performed in O(1) time. This is because they involve only pointer changes and do not require shifting of elements or traversal of the list, unlike array-based implementations where shifting may be needed.

The rear pointer keeps track of the last node in the queue. This allows us to directly add new elements to the end in constant time (O(1)). Without the rear pointer, we would have to start from the front and traverse the entire list every time we wanted to insert a new node, which would be inefficient (O(n) time).