Variables aur Types

C++ ke fundamental types mein int, double, bool, aur char shaamil hain. Har variable ka ek type hota hai, aur ek baar declare hone ke baad woh type fixed ho jaata hai. Dhyan rahe ke cout ek bool ko 0 ya 1 print karta hai, true/false words nahi, jab tak aap explicitly word form na maangein.

#include <iostream>
using namespace std;

int main() {
    int age = 30;
    double price = 19.99;
    bool isStudent = false;
    char grade = 'A';

    cout << age << " " << price << " " << isStudent << " " << grade << endl;
    return 0;
}

30 19.99 0 A

auto aur const

auto compiler ko ek variable ka type uske initializer se infer karne deta hai — useful hai jab type obvious ya verbose ho, halaanke yeh phir bhi ek fixed, fully static type produce karta hai, dynamic nahi. const ek variable ko initialization ke baad unmodifiable mark karta hai; compiler isko compile time par enforce karta hai.

#include <iostream>
using namespace std;

int main() {
    auto count = 42; // inferred as int
    auto pi = 3.14159; // inferred as double
    const int maxUsers = 100;
    cout << count << " " << pi << " " << maxUsers << endl;
    return 0;
}

42 3.14159 100

Aage: references aur pointers — ek value ko bina copy kiye refer karne ke do alag tareeqe, aur inke darmiyan ka genuinely C++-specific farq.