rust - Using an iterator in a `loop` always returns the first element - Stack Overflow

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Can somebody tell me why, in Rust, iter().next() doesn't return the next element in the list?

    let malistechaînée = [1, 2, 3];

    let mut compteur = 0usize;

    loop {
        let mut iteratoroutoffor = malistechaînée.iter();
        let chaine = iteratoroutoffor.next();

        if chaine.is_some() {
            println!("loop {}", chaine.unwrap());
        } else {
            break;
        }
        compteur += 1;
        if compteur == malistechaînée.len() {
            println!("C'EST DE LA MERDE !!!");
            break;
        }
    }

prints:

loop 1
loop 1
loop 1
C'EST DE LA MERDE !!!

With for loops it works but sometimes we just want to use loop loops just like do while or while loops in C. But, in my case, iter().next() never switches the element!

For results I got an infinite loop.

Can somebody tell me why, in Rust, iter().next() doesn't return the next element in the list?

    let malistechaînée = [1, 2, 3];

    let mut compteur = 0usize;

    loop {
        let mut iteratoroutoffor = malistechaînée.iter();
        let chaine = iteratoroutoffor.next();

        if chaine.is_some() {
            println!("loop {}", chaine.unwrap());
        } else {
            break;
        }
        compteur += 1;
        if compteur == malistechaînée.len() {
            println!("C'EST DE LA MERDE !!!");
            break;
        }
    }

prints:

loop 1
loop 1
loop 1
C'EST DE LA MERDE !!!

With for loops it works but sometimes we just want to use loop loops just like do while or while loops in C. But, in my case, iter().next() never switches the element!

For results I got an infinite loop.

• rust

Share Improve this question Follow edited Mar 14 at 12:47 cafce25 28k55 gold badges4545 silver badges5858 bronze badges asked Mar 14 at 12:02 Hurukan Imperial StepperHurukan Imperial Stepper 13722 silver badges99 bronze badges 0

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1 Answer 1

Sorted by: Reset to default 5

The problem is you create a new iterator that starts from the beginning every iteration of the loop, you should create an iterator once before the loop and reuse it:

    let malistechaînée = [1, 2, 3];

    let mut compteur = 0usize;

    let mut iteratoroutoffor = malistechaînée.iter();
    loop {
        let chaine = iteratoroutoffor.next();

        if chaine.is_some() {
            println!("loop {}", chaine.unwrap());
        } else {
            break;
        }
        compteur += 1;
        if compteur == malistechaînée.len() {
            println!("C'EST DE LA MERDE !!!");
            break;
        }
    }

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