The code below has 2 distinct while loops I used in some of my code. I was expecting the same behaviors but eventually realized that somehow the "&&" in the second while loop did not behave as I expected. See:

use std::collections::HashSet;

fn main() {
let mut hs = HashSet::new();

let arr = [Some(2), Some(3)];
let mut iter = arr.iter();

while let Some(m) = iter.next() {
    hs.insert(m);
}
println!("HashSet ==> {:?}", hs);

hs.clear();

while let Some(m) = iter.next()
    && hs.insert(m)
{
    println!("{:?}", m);
}
println!("HashSet ==> {:?}", hs);

}

Running this code displays:
HashSet ==> {Some(2), Some(3)}
HashSet ==> {}

1 post - 1 participant

Read full topic