How to Use Pointer to Structure in C: Syntax and Examples

In C, you use a pointer to structure to access structure members indirectly by storing the address of a structure variable. Use the -> operator with the pointer to access members, for example, ptr->member.

Syntax

To declare a pointer to a structure, use struct StructName *ptr;. To assign it, use the address of a structure variable: ptr = &variable;. Access members through the pointer using ptr->member, which is shorthand for (*ptr).member.

c

struct Person {
    char name[50];
    int age;
};

struct Person *ptr; // pointer to structure
struct Person person1;

ptr = &person1; // assign address of person1 to ptr

// Access members
ptr->age = 30;
(*ptr).age = 30; // equivalent to ptr->age = 30;

Example

This example shows how to create a structure, declare a pointer to it, assign the address, and access members using the pointer.

c

#include <stdio.h>

struct Person {
    char name[50];
    int age;
};

int main() {
    struct Person person1 = {"Alice", 28};
    struct Person *ptr = &person1; // pointer to person1

    // Access and print members using pointer
    printf("Name: %s\n", ptr->name);
    printf("Age: %d\n", ptr->age);

    // Modify age using pointer
    ptr->age = 29;
    printf("Updated Age: %d\n", person1.age);

    return 0;
}

Output

Name: Alice
Age: 28
Updated Age: 29

Common Pitfalls

• Forgetting to assign the pointer to a valid structure address before use causes undefined behavior.
• Using dot operator (.) with a pointer instead of arrow operator (->).
• Dereferencing a NULL or uninitialized pointer leads to crashes.

c

#include <stdio.h>

struct Point {
    int x;
    int y;
};

int main() {
    struct Point p = {10, 20};
    struct Point *ptr = NULL;

    // Wrong: Using dot operator on pointer
    // ptr.x = 15; // Error: ptr is a pointer, not a struct

    // Correct: Use arrow operator
    ptr = &p;
    ptr->x = 15;

    printf("x = %d, y = %d\n", p.x, p.y);
    return 0;
}

Output

x = 15, y = 20

Quick Reference

Pointer to Structure Cheat Sheet:

Operation	Syntax
Declare pointer	struct Type *ptr;
Assign address	ptr = &variable;
Access member	ptr->member
Equivalent access	(*ptr).member

Key Takeaways

Use the arrow operator (->) to access structure members through a pointer.

Always assign the pointer to a valid structure address before accessing members.

Dereferencing uninitialized or NULL pointers causes program crashes.

The expression ptr->member is shorthand for (*ptr).member.

Pointers to structures allow efficient access and modification of data without copying.