cargo run Compiling guessing_game v0.1.0 (file:///projects/guessing_game) Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.08s Running `target/debug/guessing_game` Hello, world +++++++ warning: `guessing_game` (bin "guessing_game") generated 1 warning Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.59s Rust 警告我们没有使用 read_line 的返回值 Result，说明有一个可能的错误没有处理。 cargo run Compiling guessing_game v0.1.0 (file:///projects/guessing_game) Finished `dev` profile [unoptimized + debuginfo] target(s) in 6.44s Running `target/debug/guessing_game` Guess the