Self-Referential Structures in C

A self-referential structure is a structure that contains a pointer to another structure of the same type. This allows structures to be chained together, forming dynamic data structures like linked lists, trees, and graphs. In simple terms: one member of the structure points to another variable of the same structure type.

Syntax

struct Node {
    int data;
    struct Node *next;   // pointer to the same struct type
};

Example: Two Linked Nodes

#include <stdio.h>

struct Node {
    int data;
    struct Node *next;   // self-referential pointer
};

int main() {
    struct Node n1, n2;

    n1.data = 10;
    n2.data = 20;

    n1.next = &n2;   // n1 points to n2
    n2.next = NULL;  // last node — points to nothing

    printf("n1 data = %d\n", n1.data);
    printf("n2 data = %d\n", n1.next->data);  // access via pointer

    return 0;
}

Output:

n1 data = 10
n2 data = 20

Visualising the Link

n1              n2
+------+----+   +------+------+
|  10  | *--+-->|  20  | NULL |
+------+----+   +------+------+

n1.next holds the address of n2. Accessing n1.next->data gives 20.

Why Self-Referential Structures Matter

They are the foundation of:

Data Structure	Description
Singly Linked List	Each node points to the next
Doubly Linked List	Each node points to both next and previous
Binary Tree	Each node has `left` and `right` child pointers
Graph (Adjacency List)	Each node has a list of neighbour pointers

These are dynamic — they can grow and shrink at runtime, unlike arrays.

Key Points

The pointer member must be struct NodeName * — a pointer to the same struct type
You cannot embed a struct inside itself (that would be infinite size), but a pointer to itself is fine
The last node in a chain always has its pointer set to NULL

Fundamentals

Functions

Array

String

Structure

Union

Pointer

File Handling

Preprocessor

Self-Referential Structures

Self-Referential Structures in C

Syntax

Example: Two Linked Nodes

Visualising the Link

Why Self-Referential Structures Matter

Key Points

​Self-Referential Structures in C

​Syntax

​Example: Two Linked Nodes

​Visualising the Link

​Why Self-Referential Structures Matter

​Key Points

Self-Referential Structures in C

Syntax

Example: Two Linked Nodes

Visualising the Link

Why Self-Referential Structures Matter

Key Points