讲动人的故事，写懂人的代码

2.5 故事3: 比较答案与点数之和

贾克强：“同学们，我们开始用三种语言来实现故事3吧！”

2.5.1 Rust版故事3

这个故事实在是轻松容易地实现了。赵可菲照着书，一下子就写好了。

@@ -1,4 +1,5 @@use rand::Rng;
+use std::cmp::Ordering;use std::io;fn main() {
@@ -16,5 +17,13 @@ fn main() {.read_line(&mut guess).expect("Failed to read line");+    let guess: u32 = guess.trim().parse().expect("Please type a number!");
+println!("You guessed: {guess}");
+
+    match guess.cmp(&sum_of_two_dice) {
+        Ordering::Less => println!("You guessed it wrong on the first try!"),
+        Ordering::Greater => println!("You guessed it wrong on the first try"),
+        Ordering::Equal => println!("You win!"),
+    }}

赵可菲：“这一行就是从Rust的标准库中引入了Ordering枚举，主要是用来做比较的哦。“

+use std::cmp::Ordering;

"这一行是把玩家输入的guess从字符串类型解析成无符号32位整数（u32），然后把空白字符都去掉。如果改不成功，就会打出"Please type a number!"的错误信息。"

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

“这段代码就是比较你猜的数字和两颗骰子上的点数之和。用cmp方法来比一比，然后返回一个Ordering枚举。根据比较的结果，会显示不一样的信息：如果你猜的数字比点数之和小，就会显示"You guessed it wrong on the first try!"。如果你猜的数字比点数之和大，也会显示"You guessed it wrong on the first try!"。要是你猜对了，就会显示"You win!"”

+    match guess.cmp(&sum_of_two_dice) {
+        Ordering::Less => println!("You guesse