Rust猜数字之比较

     extern crate rand;

     use std::io;
     use std::cmp::Ordering;
     use rand::Rng;

     fn main() {
         println!("Guess the number!");

         let secret_number = rand::thread_rng().gen_range(1, 101);

         println!("The secret number is: {}", secret_number);

         println!("Please input your guess.");

         let mut guess = String::new();

         io::stdin().read_line(&mut guess)
             .ok()
             .expect("failed to read line");

         println!("You guessed: {}", guess);

         match guess.cmp(&secret_number) {
             Ordering::Less    => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal   => println!("You win!"),
         }
     }

          match guess.cmp(&secret_number) {
             Ordering::Less    => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal   => println!("You win!"),
         }

     enum Foo{
          Bar,
          Baz,
     }

     match guess.cmp(&secret_number) {
             Ordering::Less    => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal   => println!("You win!"),
     }

     $ cargo build
        Compiling guessing_game v0.1.0 (file:///home/you/projects/guessing_game)
     src/main.rs:28:21: 28:35 error: mismatched types:
     expected `&collections::string::String`,
         found `&_`
     (expected struct `collections::string::String`,
         found integral variable) [E0308]
     src/main.rs:28     match guess.cmp(&secret_number) {
                                        ^~~~~~~~~~~~~~
     error: aborting due to previous error
     Could not compile `guessing_game`.

     extern crate rand;

     use std::io;
     use std::cmp::Ordering;
     use rand::Rng;

     fn main() {
         println!("Guess the number!");

         let secret_number = rand::thread_rng().gen_range(1, 101);

         println!("The secret number is: {}", secret_number);

         println!("Please input your guess.");
     
         let mut guess = String::new();

         io::stdin().read_line(&mut guess)
             .ok()
             .expect("failed to read line");
     
         let guess: u32 = guess.trim().parse()
             .ok()
             .expect("Please type a number!");

         println!("You guessed: {}", guess);

         match guess.cmp(&secret_number) {
             Ordering::Less    => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal   => println!("You win!"),
         }
     }

      let guess: u32 = guess.trim().parse()
             .ok()
             .expect("Please type a number!");

     guess.trim().parse()

     $ cargo run
        Compiling guessing_game v0.0.1 (file:///home/you/projects/guessing_game)
          Running `target/guessing_game`
     Guess the number!
     The secret number is: 58
     Please input your guess.
       76
     You guessed: 76
     Too big!