在匹配中分配向量的值：移动发生......它没有实现“复制”特征

Question

For convenience, you can find the below code on Rust Playground :

fn main() {
    println!("Hello, world!");
    let n = 5;
    let mut my_vector : Vec<u16>;
    
    loop {
        let x: Result<i32, &str> = Ok(-3);
        match x {
            Ok(-3) => {
                my_vector = (0..n).map(|x| x).collect();
                // works
                for e in my_vector {
                    println!("{}", e);
                }
            },
            Err(e) => {
                eprintln!("couldn't recieve a datagram: {}", e);
            },
            _ => {
            }
        }
        // does not work
        for e in my_vector {
            println!("{}", e);
        }
        break;
    }
}

I get the error " move occurs because my_vector has type Vec<u16>, which does not implement the Copy trait " and I am not able to make the program compile (and work), any help very well appreciated!

NB: This is a simplified example of the error I am facing in my program.

How could I set the value of the vector inside the match {} and then reuse it later on?

Answer 1

for e in my_vector {
    println!("{}", e);
}

This consumes my_vector . If you want to iterate the elements and still be able to use them later, you can use .iter()

for e in my_vector.iter() {
    println!("{}", e);
}

Here's a working playground: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=8c99592ef98735472165f76b6ceb9b19