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!")
    }
}

extern crate rand;

use std::io;
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!");

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

--- 
+++ 
@@ -1,6 +1,7 @@
 extern crate rand;
 
 use std::io;
+use std::cmp::Ordering;
 use rand::Rng;
 
 fn main() {
@@ -17,5 +18,14 @@
     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!")
+    }
 }
Add comparision between guess and secret_number
