rust_ex4.rs

// takes v by (immutable) reference
fn count_occurences(v: &Vec<i32>, val: i32) -> usize {
    v.into_iter().filter(|&&x| x == val).count()
}

fn main() {
    let v = vec![2, 9, 3, 1, 3, 2, 5, 5, 2];
    // borrowing v for the iteration
    for &item in &v {
        // the first borrow is still active
        // we borrow it the second time here!
        let res = count_occurences(&v, item);
        println!("{} is repeated {} times", item, res);
    }
}