Structures

Introduction

A structure (struct) groups related variables of different types under one name — ideal for records like Student or Point.

Understanding the topic

Define struct struct Name { type member; ... };

Declare variable struct Name var; or use typedef.

Access members var.member with dot operator.

• Define struct — struct Name { type member; .
• Declare variable — struct Name var; or use typedef.
• Access members — var.

Step-by-step explanation

1. Define struct — struct Name { type member; .
2. Declare variable — struct Name var; or use typedef.
3. Access members — var.

Syntax reference

Syntax reference:

struct Tag { type field; };
struct Tag v = { val1, val2 };

Informative example

Example program:

#include <stdio.h>

struct Point { int x; int y; };

int main(void) {
    struct Point p = {10, 20};
    printf("(%d, %d)\n", p.x, p.y);
    return 0;
}

(10, 20)

Execution workflow

Best practices

• Enable warnings: gcc -Wall -Wextra -std=c11 source.c -o app
• Give every variable a defined value before it is read.
• Stay inside array bounds — C will not stop you from over-running a buffer.

Common mistakes

• Reading uninitialized storage — behavior is undefined.
• Dismissing compiler warnings instead of fixing root causes.
• Ignoring NULL returns from malloc, fopen, and similar APIs.

Hands-on exercise

Practice problems:

• Student struct with name and id
• Array of structures

Summary

Structures in C — Group heterogeneous fields under one tag.