A linked list is a linear data structure composed of nodes

by Jii Yoo
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A linked list is a linear data structure composed of nodes. Each node represents a single piece of data, similar to an element in an array. However, unlike arrays—where elements are stored contiguously in memory—nodes in a linked list are scattered across memory and connected through pointers.

To traverse a list where nodes are not stored sequentially, we need to keep track of their memory addresses. A typical node consists of two attributes:

  • data – the actual value stored in the node.
  • pointer – a reference to the next node in the list.

Here’s the basic structure of a node in C:

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

The data field holds the value assigned to the node (an integer in this case). And the next pointer stores the address of the next node, allowing traversal through the list.

Since a linked list relies on pointers for navigation, overriding the next pointer of a node without preserving its original reference can break the chain, making it impossible to access subsequent nodes. This is why proper pointer management is crucial in linked lists (250204123024).

Here’s a minimal example of a linked list with three nodes (1 -> 2 -> 3):

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

// Define a Node structure
typedef struct Node {
    int data;
    struct Node *next;
} Node;

int main(int argc, char **argv) {
    // Allocate memory for the head node and check for NULL
    Node *head = malloc(sizeof(Node));

    // Initialize first node
    head->data = 1;
    head->next = malloc(sizeof(Node));

    // Initialize second node
    head->next->data = 2;
    head->next->next = malloc(sizeof(Node));

    // Initialize third node
    head->next->next->data = 3;
    head->next->next->next = NULL; // End of list

    // Traverse and print the list
    Node *curr = head;
    while (curr) {
        printf("%d\n", curr->data);
        curr = curr->next;
    }

    // Free allocated memory
    curr = head;
    while (curr) {
        Node *temp = curr->next;
        free(curr);
        curr = temp;
    }

    head = NULL; // Avoid dangling pointer

    return 0;
}
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