Cows-and-bulls-game
This program randomly generates a 4-digit number and asks you to guess the number. For every digit that the user guessed correctly in the correct place, they have a COW. For every digit the user guessed correctly in the wrong place is a BULL. Every time you make a guess, it tells you how many COWS and BULLS you have. Once the you guess the correct number, the game is over.