How to iterate over every second number

There's std::iter::range_step right now, but it's marked as unstable with the message "likely to be replaced by range notation and adapters".

fn main() {
    for i in std::iter::range_step(0, 10, 2) {
        println!("{:?}", i);
    }
}

prints

0
2
4
6
8

the itertools crate offers what you want for abitrary iterators. The step function creates an iterator that skips n-1 elements after each iteration.

use itertools::Itertools;

let mut it = (0..10).step(2);
assert_eq!(it.next(), Some(0));
assert_eq!(it.next(), Some(2));
assert_eq!(it.next(), Some(4));
assert_eq!(it.next(), Some(6));
assert_eq!(it.next(), Some(8));
assert_eq!(it.next(), None);

This is now implemented in std with the step_by function

for i in (0..10).step_by(2) {
    // Do stuff
}