Aapka Pehla Rust Program

Har Rust program ka execution main naam ke function mein shuru hota hai — yeh non-negotiable hai, JavaScript ya Python ke ulat jahan code bas top-to-bottom run ho sakta hai. println! ek macro hai (! dhyan do), function nahi, isi liye yeh aapko yahan har lesson mein dikhega.

Compiling sabse pehle hoti hai

Jab aap run dabate ho, rustc ek bhi line execute karne se pehle aapki poori file ko ek binary mein compile kar deta hai. Agar kahin bhi type error hai, borrow-checker violation hai, ya sirf ek syntax mistake bhi hai, to kuch bhi run nahi hota — aapko output ke bajaye compile error milta hai. Rust ke compiler ki reputation strict hone ki hai, lekin yahi strictness hai jo aapka code actually execute hone se pehle bugs ki poori categories ko pakad leti hai.

Comments

Comments zyadatar C-family languages ki tarah kaam karte hain: line mein // ke baad jo bhi likha ho use completely ignore kar diya jaata hai, aur yeh sirf isliye hote hain taaki baad mein code padhne wale insaan samajh sakein ki kuch is tarah kyun likha gaya hai.

Khud run karke dekho

Yeh raha ek chhota program jisme ek comment aur do println! calls hain. Neeche dikha output actually execute karke nikala gaya hai — text change karke khud bhi example ke neeche button se run karke dekho.

// This is a comment - Rust ignores it
fn main() {
    println!("Hello, World!");
    println!("Welcome to Rust.");
}

Hello, World!
Welcome to Rust.

Aage: variables aur mutability — Rust immutability ko default kaise banata hai, opt-in nahi.