03. Variables & Data Types

Box wali analogy, int/char/float, format specifiers, live labs

Goals:

Variable = named storage
int, float, char
printf format: %d %f %c

1. Variable kya hai? (simple)

Variable ek named box hai jisme value rakhte ho.

int age = 18; ka matlab:
• type = int (poora number)
• naam = age
• value = 18

Baad me age likhoge to computer us box ki value use karega.

2. Basic types

int — whole numbers (10, -3)
float — decimals (5.9)
char — single character ('A') — single quotes

Technical: type batata hai kitni memory reserve hogi aur value kaise interpret hogi.

Live practice 1 — Teen variables

Output me age, height, grade dikhne chahiye. Values change karke Run karo.

#include <cstdio>

int main() {
    int age = 18;
    float height = 5.9f;
    char grade = 'A';

    printf("Age = %d\n", age);
    printf("Height = %.1f\n", height);
    printf("Grade = %c\n", grade);
    return 0;
}

Live practice 2 — Calculation variable me

Sum variable me store karke print.

#include <cstdio>

int main() {
    int a = 10;
    int b = 25;
    int sum = a + b;
    printf("%d + %d = %d\n", a, b, sum);
    return 0;
}

Best practice: meaningful names (age, total) — x1, t se better.

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