Cool, I got it to compile on OS X and here were my results:

Welcome to Guess My Number!
Enter 0 at any time to quit
Enter the difficulty (1-3): 3
Enter your guess: 5
Too low! Try again.
Enter your guess: 100
Too low! Try again.
Enter your guess: 1000
Too high! Try again.
Enter your guess: 500
Too high! Try again.
Enter your guess: 300
Too low! Try again.
Enter your guess: 400
Too high! Try again.
Enter your guess: 350
Too high! Try again.
Enter your guess: 325
Too low! Try again.
Enter your guess: 335
Too high! Try again.
Enter your guess: 330
Too low! Try again.
Enter your guess: 333
Too high! Try again.
Enter your guess: 332

You guessed correctly after 11 attempts.
The number was: 332