Initialize new String in rust with {}

String::new can't do that. You can use the format! macro, like this:

let insert_message = format!("Please input Your guess in the range from {} to {}.", range_from, range_to);

Or, as of Rust 1.58, you can also do it like this:

let insert_message = format!("Please input Your guess in the range from {range_from} to {range_to}.");

See this for more.

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