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Rust Practice Exercises

FizzBuzz in Rust

The classic interview warm-up, solved cleanly with match on a tuple.

  • Beginner
  • 2 min read
  • 1 runnable example
What you'll learn
  • match on (n % 3, n % 5)
  • The _ pattern
  • map and join
Run code →
1 to 6
11
22
Fizz3
44
Buzz5
Fizz6

Two remainders, four cases

Print the numbers from 1 to 15, but print Fizz for multiples of 3, Buzz for multiples of 5 and FizzBuzz for multiples of both.

Matching on the tuple (n % 3, n % 5) checks both remainders at once, and _ means any value. map calls fizzbuzz for every number of the range and join puts the results on one line.

Key points

  1. (0, 0) means divisible by both.
  2. _ matches any value.
  3. Order of the arms matters.

Runnable Rust example

Rust
Run code →
main.rs
fn fizzbuzz(n: u32) -> String {
    match (n % 3, n % 5) {
        (0, 0) => String::from("FizzBuzz"),
        (0, _) => String::from("Fizz"),
        (_, 0) => String::from("Buzz"),
        _ => n.to_string(),
    }
}

fn main() {
    let line: Vec<String> = (1..=15).map(fizzbuzz).collect();
    println!("{}", line.join(" "));
}
Get a Run button for this example Result of running the code
1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz

Practice

Open the example in the online compiler, change a value or add a line, and predict the output before you run it. Then break the code on purpose and read the compiler's message.

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