代码块和作用域

块

A block in Rust contains a sequence of expressions, enclosed by braces {}. Each block has a value and a type, which are those of the last expression of the block:

1. fn main() {
2. let z = 13;
3. let x = {
4. let y = 10;
5. println!("y: {y}");
6. z - y
7. };
8. println!("x: {x}");
9. }

If the last expression ends with ;, then the resulting value and type is ().

This slide and its sub-slides should take about 5 minutes.

• 你可以通过更改块的最后一行，来展示块值的变化情况。例如，添加/移除分号或使用 return。