Simple Linked List Program in C

Creating a linked list in C involves understanding the basic concepts of pointers and dynamic memory allocation. A linked list is a collection of nodes where each node contains a data part and a pointer to the next node in the sequence. Here’s how you can create a simple linked list in C.

Creating a Simple Linked List in C

1. Define the Node Structure

First, we need to define the structure of a node in the linked list. Each node will contain an integer data field and a pointer to the next node.

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

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

2. Function to Create a New Node

Next, we need a function to create a new node. This function will allocate memory for a new node, set its data, and initialize its next pointer to NULL.

// Function to create a new node
struct Node* createNode(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}

3. Insert a Node at the Beginning

We can add a function to insert a new node at the beginning of the linked list. This function will update the head of the list to point to the new node.

// Function to insert a node at the beginning of the linked list
void insertAtBeginning(struct Node** head, int data) {
    struct Node* newNode = createNode(data);
    newNode->next = *head;
    *head = newNode;
}

4. Traverse the Linked List

To print the elements of the linked list, we need a function to traverse it.

// Function to traverse and print the linked list
void traverseList(struct Node* head) {
    struct Node* temp = head;
    while (temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}

5. Main Function to Demonstrate Linked List Operations

Finally, we can write the main function to demonstrate the creation and traversal of the linked list.

int main() {
    struct Node* head = NULL; // Initialize the head of the list

    // Insert elements at the beginning
    insertAtBeginning(&head, 3);
    insertAtBeginning(&head, 2);
    insertAtBeginning(&head, 1);

    // Traverse and print the linked list
    traverseList(head);

    return 0;
}

Complete Code

Here’s the complete code for creating and traversing a simple linked list in C:

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

// Define the node structure
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));
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}

// Function to insert a node at the beginning of the linked list
void insertAtBeginning(struct Node** head, int data) {
    struct Node* newNode = createNode(data);
    newNode->next = *head;
    *head = newNode;
}

// Function to traverse and print the linked list
void traverseList(struct Node* head) {
    struct Node* temp = head;
    while (temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}

int main() {
    struct Node* head = NULL; // Initialize the head of the list

    // Insert elements at the beginning
    insertAtBeginning(&head, 3);
    insertAtBeginning(&head, 2);
    insertAtBeginning(&head, 1);

    // Traverse and print the linked list
    traverseList(head);

    return 0;
}

Explanation

1. Node Structure: Defines a Node with an integer data and a pointer to the next node.
2. Create Node: Allocates memory for a new node, initializes its data and next pointer.
3. Insert at Beginning: Adds a new node at the beginning of the list and updates the head.
4. Traverse List: Prints each node’s data, following the next pointers until reaching the end.
5. Main Function: Demonstrates the creation of a linked list by inserting nodes and then traversing and printing the list.

By understanding and practicing this code, you’ll gain a good foundation in linked list operations in C. Happy coding!