Generate random secret number

rustbook/guessing_game/src/main.rs

@@ -1,8 +1,15 @@
+extern crate rand;
+
 use std::io;
+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();