是否可以在Rust中的函数中定义可选参数？(Is it possible to define optional arguments within functions in Rust?)

是否可以在Rust中的函数中定义可选参数？(Is it possible to define optional arguments within functions in Rust?)

Rust是否允许可选的函数参数，然后我可以将其设置为某个默认值，例如通过模式匹配或其他一些机制？

Does Rust allow for optional function arguments, which I can then set to some default value, such as through pattern matching or some other mechanism?

最满意答案

技术上没有，但你可以捎带Option枚举，它始终可用于实现类似的效果：

fn opt_arg(i: Option<int>) { match i { Some(x) => { println!("Got {}", x); }, None => { println!("Didn't get anything"); } } } fn main() { opt_arg(None); // Didn't get anything opt_arg(Some(2i)); // Got 2 }

Technically no, but you can piggyback off the Option enum which is always available to achieve a similar effect:

fn opt_arg(i: Option<int>) { match i { Some(x) => { println!("Got {}", x); }, None => { println!("Didn't get anything"); } } } fn main() { opt_arg(None); // Didn't get anything opt_arg(Some(2i)); // Got 2 }