Data Types in C - Complete Guide

🧠 What Are Data Types in C?

Data types tell the compiler what kind of data a variable will store — like numbers, characters, or decimals.

Think of data types as different boxes 📦 to store different kinds of items: numbers, letters, decimals, etc.

🧱 Main Categories of Data Types

1️⃣ int (Integer)

Used to store whole numbers.

#include <stdio.h>

int main() {
    int age = 20;
    printf("Age: %d\n", age);
    return 0;
}

%d is used for printing integer values.

2️⃣ float (Decimal)

Used for decimal numbers with ~6 digits of precision.

#include <stdio.h>

int main() {
    float pi = 3.14;
    printf("Value of pi: %.2f\n", pi);
    return 0;
}

%.2f prints float with 2 decimal places.

3️⃣ double (More precise decimal)

Used for more accurate decimals than float.

#include <stdio.h>

int main() {
    double price = 99.999999;
    printf("Price: %.6lf\n", price);
    return 0;
}

%.6lf is used for printing double values.

4️⃣ char (Character)

Used to store a single character.

#include <stdio.h>

int main() {
    char grade = 'A';
    printf("Your grade is: %c\n", grade);
    return 0;
}

%c is used to print characters.

5️⃣ void (No value)

Used in functions that don’t return anything.

#include <stdio.h>

void sayHello() {
    printf("Hello, World!\n");
}

int main() {
    sayHello();
    return 0;
}

void means the function doesn’t give anything back.

🧮 Summary Table

✅ Final Tips

• Use int for counting, marks, age, etc.
• Use float or double when dealing with decimals and precision.
• Use char for single letters or symbols.
• void is mostly used in functions with no return value.