Enum tao_of_rust::ch02::generics_trait::Option

pub enum Option<T> {
    Some(T),
    None,
}

std::option::Option 定义

Basic usage:

use std::fmt::Debug;
fn match_option<T: Debug>(o: Option<T>) {
    match o {
        Some(i) => println!("{:?}", i),
        None => println!("nothing"),
    }
}
let a: Option<i32> = Some(3);
let b: Option<&str> = Some("hello");
let c: Option<char> = Some('A');
let d: Option<u32>  = None;

match_option(a);  // 3
match_option(b);  // "hello"
match_option(c);  // 'A'
match_option(d);  // nothing

Variants

Some(T)None