看里面的元组

要直接访问元组的元素，可以使用 .n 格式访问 n-th 元素

let x = ("hello", 42, true);
assert_eq!(x.0, "hello");
assert_eq!(x.1, 42);
assert_eq!(x.2, true);

你也可以部分移出一个元组

let x = (String::from("hello"), 42);
let (s, _) = x;
let (_, n) = x;
println!("{}, {}", s, n);
// the following would fail however, since x.0 has already been moved
// let foo = x.0;