How to Create Linked List Using Structure in C: Simple Guide

To create a linked list in C, define a struct with data and a pointer to the next node. Then, dynamically allocate nodes and link them by setting the pointer to the next node's address.

Syntax

A linked list node is created using a struct that contains two parts: the data and a pointer to the next node. The pointer connects nodes to form the list.

• struct Node: Defines the node structure.
• data: Holds the value (e.g., int).
• next: Pointer to the next node in the list.

c

struct Node {
    int data;
    struct Node* next;
};

Example

This example creates a linked list with three nodes, assigns values, and prints them in order.

c

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

struct Node {
    int data;
    struct Node* next;
};

int main() {
    struct Node* head = NULL;
    struct Node* second = NULL;
    struct Node* third = NULL;

    // Allocate memory for nodes
    head = (struct Node*)malloc(sizeof(struct Node));
    second = (struct Node*)malloc(sizeof(struct Node));
    third = (struct Node*)malloc(sizeof(struct Node));

    // Assign data and link nodes
    head->data = 10;
    head->next = second;

    second->data = 20;
    second->next = third;

    third->data = 30;
    third->next = NULL;

    // Print linked list
    struct Node* current = head;
    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }

    // Free memory
    free(third);
    free(second);
    free(head);

    return 0;
}

Output

10 20 30 

Common Pitfalls

Common mistakes when creating linked lists include:

• Not allocating memory with malloc, causing crashes.
• Forgetting to set the last node's next pointer to NULL, leading to undefined behavior.
• Not freeing allocated memory, causing memory leaks.
• Mixing up -> and . operators when accessing struct members through pointers.

c

/* Wrong: Missing malloc causes crash */
struct Node* node;
// node->data = 5; // Error: node is not allocated

/* Right: Allocate before use */
node = (struct Node*)malloc(sizeof(struct Node));
node->data = 5;
node->next = NULL;

Quick Reference

Remember these key points when working with linked lists in C:

• Define a struct with data and a pointer to the next node.
• Use malloc to create nodes dynamically.
• Link nodes by setting the next pointer.
• Set the last node's next to NULL.
• Free allocated memory after use to avoid leaks.

Key Takeaways

Define a struct with data and a pointer to the next node to create linked list nodes.

Always allocate memory for nodes using malloc before using them.

Link nodes by setting the next pointer to the following node's address.

Set the last node's next pointer to NULL to mark the list end.

Free all allocated memory to prevent memory leaks.