trpl-zh-cn/listings/ch04-understanding-ownership/no-listing-18-first-word-slice/src/main.rs

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

    for (i, &item) in bytes.iter().enumerate() {
        if item == b' ' {
            return &s[0..i];
        }
    }

    &s[..]
}
// ANCHOR_END: here

fn main() {}