Summary - Rust basics

Combine fn main, println! and comments to write your first program.

Rust basics summary

In this group you learned Rust's goal (safety + speed), project management with Cargo (cargo new, run, build --release, test), the fn main entry point, the println!/print!/eprintln! macros, the {}/{:?}/{:.2} formats and the three kinds of comments.

fn main() {
    let dil = "Rust";
    let yil = 2015;
    println!("{dil} {yil} yılında 1.0 oldu");
}

The compiler is your friend

The Rust compiler's error messages are detailed: they point at the problem line, explain why, and often suggest a fix. Commands such as rustc --explain E0382 give a long explanation of each error code. cargo clippy provides extra suggestions and cargo fmt standard formatting.

Exercise Introduction line

Declare let dil = "Rust"; and let yil = 2015;. Print println!("{dil} {yil} yılında 1.0 oldu"); and add an explanatory // comment before it.

Show example solution

fn main() {
    let dil = "Rust";
    let yil = 2015;
    // 1.0 sürümünün yılını yazdır
    println!("{dil} {yil} yılında 1.0 oldu");
}

Test yourself

Which doesn't compile?
- println!("{} {}", 1);
- println!("{}", 1);
- println!("{:?}", (1, 2));
- print!("a");
Show answer

println!("{} {}", 1); — There are two placeholders but only one argument; println! catches this at compile time.

Format

cargo ____   # formats the code to the standard style

Show answer

cargo fmt   # formats the code to the standard style

Tool and role

cargo fmt

Formatting
cargo clippy

Suggestions (lint)
rustc --explain

Error explanation
cargo doc

Documentation

Next lesson: Variables with let

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