How to Create a Circular Linked List in C?

// C Program to illustrate how to create a circular linked
// list
#include <stdio.h>
#include <stdlib.h>

// Define the structure for a node
struct Node {
    int data;
    struct Node* next;
};

// Function to insert a new node at the end of the list
struct Node* insertAtEnd(struct Node* last, int data)
{
    struct Node* newNode
        = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;

    if (last == NULL) {
        // If the list is empty, make the new node the only
        // node in the list
        last = newNode;
        newNode->next = last;
    }
    else {
        // Add the new node to the end and update the last
        // node's next pointer
        newNode->next = last->next;
        last->next = newNode;
        last = newNode; // Update the last pointer to the
                        // new node
    }

    return last; // Return the updated last pointer
}

// Function to display the circular linked list
void display(struct Node* last)
{
    if (last == NULL) {
        printf("List is empty.\n");
        return;
    }

    struct Node* temp
        = last->next; // Start from the first node

    do {
        printf("%d ", temp->data);
        temp = temp->next;
    } while (temp != last->next);

    printf("\n");
}

int main()
{
    struct Node* last
        = NULL; // Initialize an empty circular linked list

    // Insert nodes at the end
    last = insertAtEnd(last, 10);
    last = insertAtEnd(last, 20);
    last = insertAtEnd(last, 30);

    // Display the circular linked list
    printf("Circular Linked List: ");
    display(last);

    return 0;
}