02 Hello World

Goal

Understand the basic structure of a Rust program and the println! macro.

Steps

1. Create Project

cargo new hello_world
cd hello_world

2. Examine src/main.rs

fn main() {
    println!("Hello, world!");
}

Key points:

• fn main() - entry point, no args, no return
• println! - macro (note !), prints to stdout with newline

3. Run

cargo run

Output:

Hello, world!

4. Build for Release

cargo build --release
./target/release/hello_world

Checkpoint

Create a program that prints your name:

fn main() {
    println!("Hello, Alice!");
}

Run with cargo run - should output Hello, Alice!

Next

Continue to 03 Variables and Mutability.