環境

• Time 2022-03-25
• Rust 1.59.0

示例

as_deref

fn main() {
    let result: Result<String, u32> = Ok("ok".to_owned());
    let result: Result<&str, &u32> = result.as_deref();
    println!("{:?}", result);
}

iter

fn main() {
    let result: Result<&str, u32> = Ok("ok");
    println!("{:?}", result.iter().next());
}
 

expect

fn main() {
    let result: Result<&str, u32> = Ok("ok");
    println!("{:?}", result.expect("錯誤"));
}

unwrap

fn main() {
    let result: Result<&str, u32> = Ok("ok");
    println!("{:?}", result.unwrap());
}

unwrap_or_default

fn main() {
    let result: Result<&str, u32> = Err(44);
    println!("{:?}", result.unwrap_or_default());
}
 

expect_err

fn main() {
    let result: Result<&str, u32> = Err(44);
    println!("{:?}", result.expect_err("OK"));
}

unwrap_err

fn main() {
    let result: Result<&str, u32> = Err(44);
    println!("{:?}", result.unwrap_err());
}

and

fn main() {
    let result: Result<u32, u32> = Ok(44);
    println!("{:?}", result.and(Ok(4)));
}
 

and_then

fn main() {
    let result: Result<u32, u32> = Ok(44);
    let result: Result<u32, u32> = result.and_then(|e| Err(e * 2));
    println!("{:?}", result);
}

總結

瞭解了結果列舉中相關的一些方法。

附錄