fn string_slice(arg: &str) { println!("{arg}"); } fn string(arg: String) { println!("{arg}"); } fn main() { string_slice("blue"); string("red".to_string()); string(String::from("hi")); string("rust is fun!".to_owned()); // Here, both answers work. // `.into()` converts a type into an expected type. // If it is called where `String` is expected, it will convert `&str` to `String`. // But if is called where `&str` is expected, then `&str` is kept `&str` since no // conversion is needed. string("nice weather".into()); string_slice("nice weather".into()); // ^^^^^^^ the compiler recommends removing the `.into()` // call because it is a useless conversion. string(format!("Interpolation {}", "Station")); // WARNING: This is byte indexing, not character indexing. // Character indexing can be done using `s.chars().nth(INDEX)`. string_slice(&String::from("abc")[0..1]); string_slice(" hello there ".trim()); string("Happy Monday!".replace("Mon", "Tues")); string("mY sHiFt KeY iS sTiCkY".to_lowercase()); }