📦 Variables & Data Types in C

Learn How Computers Store Information

Complete Beginner Guide With Examples 🚀

🚀 Introduction

In the previous lesson, we created our first C program using printf().

But programs need to store information such as numbers, names, marks, and calculations. For this purpose, we use Variables.

"A variable is a named memory location used to store data."

📦 What is a Variable?

A variable is like a container where a computer stores information.

Example:

int age = 25;

Here:

• int → Data type
• age → Variable name
• 25 → Stored value

🧠 How Variables Work in Memory

Computer Memory

┌───────────────┐
│ age = 25 │
└───────────────┘

The computer assigns a memory location to every variable.

🔢 Data Types in C Programming

Data types define what type of information a variable can store.

🔢 int

Stores whole numbers.

int marks = 90;

📊 float

Stores decimal numbers.

float price = 99.5;

🔤 char

Stores a single character.

char grade='A';

📝 double

Stores large decimal values.

double pi=3.14159;

💻 Example: Using Variables in C

#include <stdio.h>

int main()
{

    int age = 20;
    float height = 5.8;
    char grade = 'A';

    printf("Age = %d", age);

    printf("\nHeight = %.1f", height);

    printf("\nGrade = %c", grade);

    return 0;

}

🖥️ Output

Age = 20
Height = 5.8
Grade = A

📌 Rules for Naming Variables

• Variable name cannot start with a number
• No spaces are allowed
• Use meaningful names
• C keywords cannot be used
• C language is case-sensitive

Correct examples:

studentName
totalMarks
accountBalance

🔒 Constants in C

A constant is a value that cannot be changed during program execution.

const int DAYS = 7;

⭐ Why Are Variables Important?

• Store user information
• Perform calculations
• Manage program data
• Create dynamic applications
• Build complex software

🎯 Conclusion

Variables and data types are the building blocks of C programming. Understanding them is essential before learning advanced topics.

Next: Operators in C Programming ➕➖✖️