Summary - Rust basics
- Rust course
- Beginner
- Lesson 6/115
- 5 min
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.
Practice 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.
Starter code
fn main() {
// buraya yaz
}Sample solution
fn main() {
let dil = "Rust";
let yil = 2015;
// 1.0 sürümünün yılını yazdır
println!("{dil} {yil} yılında 1.0 oldu");
}Expected output
Rust 2015 yılında 1.0 oldu
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which doesn't compile?
- println!("{} {}", 1); Correct answer
- println!("{}", 1);
- println!("{:?}", (1, 2));
- print!("a");
Explanation: There are two placeholders but only one argument; println! catches this at compile time.
2 Format
cargo ____ # formats the code to the standard stylecargo fmt # formats the code to the standard styleExplanation: cargo fmt formats the code to the standard style with rustfmt.
3 Tool and role
| Term | Meaning |
|---|---|
cargo fmt |
Formatting |
cargo clippy |
Suggestions (lint) |
rustc --explain |
Error explanation |
cargo doc |
Documentation |