Rust by Example

A match guard can be added to filter the arm.

fn main() {

let pair = (2, -2);

// TODO ^ Try different values for `pair`

println!("Tell me about {:?}", pair);

match pair {

(x, y) if x == y => println!("These are twins"),

// The ^ `if condition` part is a guard

(x, y) if x + y == 0 => println!("Antimatter, kaboom!"),

(x, _) if x % 2 == 1 => println!("The first one is odd"),

_ => println!("No correlation..."),

}

}

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Note that the compiler does not check arbitrary expressions for whether all possible conditions have been checked. Therefore, you must use the _ pattern at the end.

fn main() {

let number: u8 = 4;

match number {

i if i == 0 => println!("Zero"),

i if i > 0 => println!("Greater than zero"),

_ => println!("Fell through"), // This should not be possible to reach

}

}

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