Data Types in C Programming (Complete Guide with Examples)

This tutorial explains data types in C programming, which define the type and size of data a variable can store. It covers basic, derived, and user-defined data types with syntax and examples to help beginners understand memory usage and correct data representation in C programs.

1. What Are Data Types in C

Data types specify:

  1. The type of data a variable can store
  2. The amount of memory allocated
  3. The operations that can be performed on the data

2. Classification of Data Types in C

C data types are broadly classified into:

  1. Basic (Primary) Data Types
  2. Derived Data Types
  3. User-defined Data Types

3. Basic (Primary) Data Types

3.1 int

Used to store whole numbers.


int age = 25;

Typical size: 4 bytes

3.2 float

Used to store decimal values with single precision.


float price = 99.75;

Typical size: 4 bytes

3.3 double

Used to store decimal values with double precision.


double distance = 12345.6789;

Typical size: 8 bytes

3.4 char

Used to store a single character.


char grade = 'A';

Typical size: 1 byte

Example Program (Basic Data Types)


#include <stdio.h>

int main() {
int count = 10;
float rate = 5.5;
double total = 1234.5678;
char status = 'Y';

printf("Count: %d\n", count);
printf("Rate: %.2f\n", rate);
printf("Total: %.4lf\n", total);
printf("Status: %c\n", status);

return 0;
}

4. Type Modifiers

Type modifiers change the size or range of basic data types.

Modifiers:

  1. short
  2. long
  3. signed
  4. unsigned

Examples


short int a = 10;
long int b = 100000;
unsigned int c = 50;

5. Derived Data Types

Derived data types are created using basic data types.

5.1 Arrays


int marks[5] = {80, 85, 90, 75, 88};

5.2 Pointers


int x = 10;
int *ptr = &x;

5.3 Functions


int add(int a, int b) {
return a + b;
}

6. User-defined Data Types

6.1 struct


struct Student {
int id;
char name[20];
};

6.2 union


union Data {
int i;
float f;
};

6.3 enum


enum Day {Mon, Tue, Wed, Thu, Fri};

6.4 typedef


typedef unsigned int uint;
uint count = 10;

7. void Data Type

void represents the absence of a value.

Example:


void display() {
printf("Hello");
}

8. Size of Data Types

Use sizeof operator to find memory size.


printf("Size of int: %lu\n", sizeof(int));

Key Points to Remember

  1. Choose correct data type to optimize memory
  2. Use sizeof to verify memory usage
  3. Understand type modifiers for system-level programming