Circular Linked List

In a Circular Linked List, the tail node's next pointer does not point to NULL. Instead it loops back to the head, creating a circular structure.

Structure

HEAD -> [10] -> [20] -> [30] -> [40]
         |________________________|

Types

Singly Circular — each node has only next; tail->next = head
Doubly Circular — each node has prev and next; tail->next = head AND head->prev = tail

Key Properties

No NULL — traversal never reaches null; you stop when you loop back to head
Any node can be head — useful for round-robin scheduling
Infinite loop risk — must track the starting node when traversing

Use Cases

CPU scheduling (Round Robin)
Multiplayer turn-based games
Music playlist loop
Browser tab cycling

Detecting end of traversal

Instead of while (temp != NULL), use a do-while:

do {
    // process temp->data
    temp = temp->next;
} while (temp != head);