函数

1. fn gcd(a: u32, b: u32) -> u32 {
2. if b > 0 {
3. gcd(b, a % b)
4. } else {
5. a
6. }
7. }

9. fn main() {
10. println!("gcd: {}", gcd(143, 52));
11. }

This slide should take about 3 minutes.

• 类型跟随在声明的参数后（与某些编程语言相反），然后是返回类型。
• The last expression in a function body (or any block) becomes the return value. Simply omit the ; at the end of the expression. The return keyword can be used for early return, but the “bare value” form is idiomatic at the end of a function (refactor gcd to use a return).
• 有些函数没有返回值，会返回“单元类型（unit type）”()。如果省略了-> ()的返回类型，编译器将会自动推断。
• Overloading is not supported — each function has a single implementation.
• 始终采用固定数量的参数。不支持默认参数。宏可用于支持可变函数。
• Always takes a single set of parameter types. These types can be generic, which will be covered later.