fn first_word(s: &String) -> &str {
    let bytes = s.as_bytes();

    for (i, &item) in bytes.iter().enumerate() {
        if item == b' ' {
	    return &s[..i]
	}
    }

    &s[..]
}

fn main() {
    let s = String::from("Hello world");

    println!("String: {}", s);
    println!("First word: {}", first_word(&s));
}