环境

• Rust 1.56.1
• VSCode 1.61.2

概念

参考：https://doc.rust-lang.org/stable/rust-by-example/std/option.html

示例

main.rs

fn checked_division(dividend: i32, divisor: i32) -> Option<i32> {
    if divisor == 0 {
        None
    } else {
        Some(dividend / divisor)
    }
}

fn try_division(dividend: i32, divisor: i32) {
    match checked_division(dividend, divisor) {
        None => println!("{} / {} failed!", dividend, divisor),
        Some(quotient) => {
            println!("{} / {} = {}", dividend, divisor, quotient)
        }
    }
}

fn main() {
    try_division(4, 2);
    try_division(1, 0);

    let none: Option<i32> = None;
    let _equivalent_none = None::<i32>;

    let optional_float = Some(0f32);

    println!(
        "{:?} unwraps to {:?}",
        optional_float,
        optional_float.unwrap()
    );

    // none unwrap 会 panic
    println!("{:?} unwraps to {:?}", none, none.unwrap());
}

总结

了解了 Rust 中标准库中的 Option 的使用。

附录