1fn main() {
 2    let s = String::from("hello world");
 3    let word = first_word(&s);
 4
 5    // let hello = &s[0..5];
 6    // let world = &s[6..11];
 7
 8    // s.clear();
 9    println!("word: {word} in {s}");
10}
11
12fn first_word(s: &str) -> &str {
13    let bytes = s.as_bytes();
14
15    for (i, &item) in bytes.iter().enumerate() {
16        if item == b' ' {
17            return &s[0..i];
18        }
19    }
20
21    return &s[..];
22}