# Guards

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..."),
        }
    }

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
        }
    }

### See also:

Tuples