Practice

Rust exercises

Make a change, predict what it will do, and compare the result.

1
Rust Basics
Bind values and print them.
Adapt the lesson example. Change one value or element, predict the result, and explain why it changes.
Review lesson →
Show starting example
Rust
```
fn main() {
    let name = "Ada";
    println!("Hello, {}", name);
}
```
2
Rust Ownership
Borrow a string without moving it.
Adapt the lesson example. Change one value or element, predict the result, and explain why it changes.
Review lesson →
Show starting example
Rust
```
fn show(value: &str) {
    println!("{}", value);
}
fn main() {
    let name = String::from("Ada");
    show(&name);
    println!("{}", name);
}
```
3
Rust Variables, Mutability, and Shadowing
Bindings are immutable by default; mut and shadowing change that.
Predict the output if the last arithmetic line were let count = count + 1;
Reveal answer and reasoning
count is 3 before it, so the new binding is 4 and it prints 4.
Review lesson →
Show starting example
Rust
```
fn main() {
    let mut count = 1;
    count += 2;
    let count = count * 10;
    println!("{}", count);
}
```
4
Rust Enums and match
Model alternatives with an enum and handle each one with match.
Add a Rectangle(u32, u32) variant.
Reveal answer and reasoning
Add Rectangle(u32, u32) to the enum and the arm Shape::Rectangle(w, h) => w * h, otherwise match will not compile.
Review lesson →
Show starting example
Rust
```
enum Shape {
    Circle(u32),
    Square(u32),
}

fn area(shape: &Shape) -> u32 {
    match shape {
        Shape::Circle(r) => 3 * r * r,
        Shape::Square(s) => s * s,
    }
}

fn main() {
    println!("{}", area(&Shape::Circle(2)));
    println!("{}", area(&Shape::Square(5)));
}
```
5
Rust Vectors
Store a growable list with Vec and sum it with an iterator.
Print the average as a float.
Reveal answer and reasoning
Convert both values: total as f64 / scores.len() as f64 gives 86.
Review lesson →
Show starting example
Rust
```
fn main() {
    let mut scores = vec![82, 91, 76];
    scores.push(95);
    let total: i32 = scores.iter().sum();
    println!("{} {}", scores.len(), total);
}
```

Rust Basics

Rust Ownership

Rust Variables, Mutability, and Shadowing

Rust Enums and match

Rust Vectors