Add Node to Linked List in C

#include <stdio.h>
#include <stdlib.h>

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

// Function to create a new node
struct Node* createNode(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    if (newNode == NULL) {
        printf("Memory allocation failed.\n");
        exit(1);
    }
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}

// Function to add a node to the end of the linked list
void appendNode(struct Node** head, int data) {
    struct Node* newNode = createNode(data);

    // If the linked list is empty, make the new node the head
    if (*head == NULL) {
        *head = newNode;
        return;
    }

    // Traverse to the end of the linked list
    struct Node* current = *head;
    while (current->next != NULL) {
        current = current->next;
    }

    // Append the new node to the end
    current->next = newNode;
}

// Function to display the linked list
void displayList(struct Node* head) {
    struct Node* current = head;
    while (current != NULL) {
        printf("%d -> ", current->data);
        current = current->next;
    }
    printf("NULL\n");
}

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

    // Add nodes to the linked list
    appendNode(&head, 10);
    appendNode(&head, 20);
    appendNode(&head, 30);

    // Display the linked list
    printf("Linked List: ");
    displayList(head);

    return 0;
}