# Slice patterns

If you want to match against a slice or array, you can use `&` with the `slice_patterns` feature:

#![feature(slice_patterns)] fn main() { let v = vec!["match_this", "1"]; match &v[..] { ["match_this", second] => println!("The second element is {}", second), _ => {}, } }

    #![feature(slice_patterns)]

    fn main() {
        let v = vec!["match_this", "1"];

        match &v[..] {
            ["match_this", second] => println!("The second element is {}", second),
            _ => {},
        }
    }

The `advanced_slice_patterns` gate lets you use `..` to indicate any number of elements inside a pattern matching a slice. This wildcard can only be used once for a given array. If there's an identifier before the `..`, the result of the slice will be bound to that name. For example:

#![feature(advanced_slice_patterns, slice_patterns)] fn is_symmetric(list: &[u32]) -> bool { match list { [] | [_] => true, [x, inside.., y] if x == y => is_symmetric(inside), _ => false } } fn main() { let sym = &[0, 1, 4, 2, 4, 1, 0]; assert!(is_symmetric(sym)); let not_sym = &[0, 1, 7, 2, 4, 1, 0]; assert!(!is_symmetric(not_sym)); }

    #![feature(advanced_slice_patterns, slice_patterns)]

    fn is_symmetric(list: &[u32]) -> bool {
        match list {
            [] | [_] => true,
            [x, inside.., y] if x == y => is_symmetric(inside),
            _ => false
        }
    }

    fn main() {
        let sym = &[0, 1, 4, 2, 4, 1, 0];
        assert!(is_symmetric(sym));

        let not_sym = &[0, 1, 7, 2, 4, 1, 0];
        assert!(!is_symmetric(not_sym));
    }