if
https://doc.rust-lang.org/book/if.html
カッコが無くても問題ない。
fn main() { let x = 5; if x == 5 { println!("x is five!"); } if (x == 5) { println!("x is five!"); } }
逆にカッコをつけると警告が・・・
$ cargo run warning: unnecessary parentheses around `if` condition, #[warn(unused_parens)] on by default --> src/main.rs:7:8 | 7 | if (x == 5) { | ^^^^^^^^ x is five! x is five!