fizzbuzz-match.md

Fizzbuzz with match

In this exercise you will modify your previously written fizzbuzz to use match statements instead of if statements.

After completing this exercise you are able to

• use match statements
• define a tuple

Prerequisites

For completing this exercise you need to have

• a working fizzbuzz

Task

Rewrite the body of fn fizzbuzz() so the different cases are not distinguished with if statements, but with pattern matching of a tuple containing the remainders.

If you need it, we have provided a complete solution for this exercise.

Knowledge

Tuple

A tuple is a collection of values of different types. Tuples are constructed using parentheses (), and each tuple itself is a value with type signature (T1, T2, ...), where T1, T2 are the types of its members. Functions can use tuples to return multiple values, as tuples can hold any number of values, including the _ placeholder

// A tuple with a bunch of different types.
let long_tuple = (1u8, 2u16, 3u32, 4u64,
                      -1i8, -2i16, -3i32, -4i64,
                      0.1f32, 0.2f64,
                      'a', true);

Step-by-Step-Solution

We assume you have deleted the entire function body of fn fizzbuzz() before you get started.

Step 1: The Tuple

Define a tuple that consists of the remainder of the integer i divided by 3 and the integer i divided by 5.

Solution

# let i = 10;
let remainders = (i%3, i%5);

Step 2: Add the match statement with its arms

The the for us relevant patterns of the tuple that we match for are a combination of 0 and the placeholder _ (underscore). _ stands for any value. Think about what combinations of 0 and _ represent which rules. Add the match arms accordingly.

Solution

# fn fizzbuzz(i: i32) -> String {
# let remainders = (i%3, i%5);

    match remainders {
        (0, 0) => format!("FizzBuzz"),
        (0, _) => format!("Fizz"),
        (_, 0) => format!("Buzz"),
        (_, _) => format!("{}", i),
    }
# }