extern crate rand;

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

fn main() {
    println!("Hello in my guessing game!");

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

    println!("The secret number is: {}", secret_number);
    loop {
        println!("Input your guess, please:");

        let mut guess = String::new();

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

        let guess: u32 = guess.trim().parse()
            .expect("It's not a valid number :(");

        println!("Your guess is: {}", guess);

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

extern crate rand;

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

fn main() {
    println!("Hello in my guessing game!");

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

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

    println!("Input your guess, please:");

    let mut guess = String::new();

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

    let guess: u32 = guess.trim().parse()
        .expect("It's not a valid number :(");

    println!("Your guess is: {}", guess);

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

--- 
+++ 
@@ -10,22 +10,23 @@
     let secret_number = rand::thread_rng().gen_range(1, 101);
 
     println!("The secret number is: {}", secret_number);
+    loop {
+        println!("Input your guess, please:");
 
-    println!("Input your guess, please:");
+        let mut guess = String::new();
 
-    let mut guess = String::new();
+        io::stdin().read_line(&mut guess)
+            .expect("Failed to read line!");
 
-    io::stdin().read_line(&mut guess)
-        .expect("Failed to read line!");
+        let guess: u32 = guess.trim().parse()
+            .expect("It's not a valid number :(");
 
-    let guess: u32 = guess.trim().parse()
-        .expect("It's not a valid number :(");
+        println!("Your guess is: {}", guess);
 
-    println!("Your guess is: {}", guess);
-
-    match guess.cmp(&secret_number) {
-        Ordering::Less    => println!("Too low!"),
-        Ordering::Greater => println!("Too big!"),
-        Ordering::Equal   => println!("Great guess! You win!")
+        match guess.cmp(&secret_number) {
+            Ordering::Less => println!("Too low!"),
+            Ordering::Greater => println!("Too big!"),
+            Ordering::Equal => println!("Great guess! You win!")
+        }
     }
 }
Add loop to allow multiple guesses
