Introduction to Programming in C

📘 Variables and Data Types in C

In C, variables are containers used to store data values. Each variable has a specific data type, which determines what kind of data it can store — like integers, characters, or floating-point numbers. Let's understand how to declare, use, and manage different data types in C.

🔹 What is a Variable?

A variable in C is a named space in memory that stores data. Think of it as a labeled box where you can put a value and use it later.

🔹 Declaring a Variable

int age;
float price;
char grade;

You must declare a variable before using it. You can also assign a value at the time of declaration:

int age = 21;
float price = 99.50;
char grade = 'A';

🔹 Types of Variables

• Local Variables: Declared inside a function and accessible only there
• Global Variables: Declared outside all functions, accessible throughout the program
• Static Variables: Retains its value between function calls
• Register Variables: Stored in CPU registers for faster access (optional)

📊 Common Data Types in C

💡 Example Program

#include <stdio.h>

int main() {
    int age = 20;
    float marks = 89.5;
    char grade = 'A';

    printf("Welcome to UdaanPath!\n");
    printf("Age: %d\n", age);
    printf("Marks: %.2f\n", marks);
    printf("Grade: %c\n", grade);

    return 0;
}

📝 Format Specifiers in printf()

• %d → for integers
• %f → for floats
• %.2f → float with 2 decimal places
• %c → for characters
• %s → for strings

🧠 Tips

• Initialize variables before use — uninitialized variables contain garbage values.
• Choose meaningful variable names: int score; is better than int x;
• Keep an eye on memory size: float takes less space than double

✅ Coming Next

In the next chapter, we’ll explore how to accept user input in C using functions like scanf().