`for` loops

The for loop is closely related to the while let loop. It will automatically call into_iter() on the expression and then iterate over it:

fn main() {
    let v = vec![10, 20, 30];

    for x in v {
        println!("x: {x}");
    }
    
    for i in (0..10).step_by(2) {
        println!("i: {i}");
    }
}

You can use break and continue here as usual.

Index iteration is not a special syntax in Rust for just that case.
(0..10) is a range that implements an Iterator trait.
step_by is a method that returns another Iterator that skips every other element.
Modify the elements in the vector and explain the compiler errors. Change vector v to be mutable and the for loop to for x in v.iter_mut().