Control flow based on pattern matching.
match can be used to run code conditionally. Every pattern must be handled exhaustively either explicitly or by using wildcards like _ in the match. Since match is an expression, values can also be returned.
let opt = Option::None::<usize>;
let x = match opt {
Some(int) => int,
None => 10,
};
assert_eq!(x, 10);
let a_number = Option::Some(10);
match a_number {
Some(x) if x <= 5 => println!("0 to 5 num = {}", x),
Some(x @ 6..=10) => println!("6 to 10 num = {}", x),
None => panic!(),
// all other numbers
_ => panic!(),
}match can be used to gain access to the inner members of an enum and use them directly.
enum Outer {
Double(Option<u8>, Option<String>),
Single(Option<u8>),
Empty
}
let get_inner = Outer::Double(None, Some(String::new()));
match get_inner {
Outer::Double(None, Some(st)) => println!("{}", st),
Outer::Single(opt) => println!("{:?}", opt),
_ => panic!(),
}For more information on match and matching in general, see the Reference.
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/keyword.match.html