quest – Rust: Variables

Core Beginner

00 Variables

Rust bindings are immutable unless you say otherwise, and constants carry an explicit type.

Step 3 / 3

Shadow n: parse the text into a number, then shadow again with the doubled value.

Hints

Shadowing: a second let n = ... makes a NEW binding -- even with a different type.
n.trim().parse::<i32>().unwrap() turns the text into a number.

00_variables.rs

// The input arrives as text. Shadow `n` with the parsed number,
// then shadow it again with the doubled value. Same name each time.
fn parse_and_double(n: &str) -> i32 {
    // let n = ...;   // parse it
    // let n = ...;   // double it
    todo!()
}

Reset to starterCompiled in a sandbox; hidden checks must pass.

Reveal solution

fn parse_and_double(n: &str) -> i32 {
    let n: i32 = n.trim().parse().unwrap();
    let n = n * 2;
    n
}