The good ol' guess the secret number game done in Python.

GuessTheNumber.py

import random

rand = random.randint(1000, 9999)
attempts = 0

# print rand

def check_proximity(num, guess):
    """
    :param str num: The generated random integer casted as a string.
    :param str guess: The user input, casted as a string.
    """
    black, white = 0, 0
    for i in range(len(num)):
        for j in range(len(guess)):
            if guess[i] == num[j]:
                if i == j:
                    black += 1
                elif guess[j] == num[j]: # if rand has repetition like 4660
                    white == white      
                else:
                    white += 1
    
    print "%d black, %d white" % (black, white)


while True:
    try:
        user_input = int(raw_input("Enter a 4-digit guess: "))
        attempts += 1
    except ValueError:
        print("Only numbers are allowed as input!")
        continue
    
    if user_input == int(rand):
        print "Your guess '%s' is corrrect! Attempts: %d" % (rand, attempts)
        break
    elif not 1000 <= user_input <= 9999:
        print("The range must be between 1000 and 9999. Try {}"
              .format("lower" if user_input > 9999 else "higher"))
    else:
        # Cast int to str so that indices can be used to check the digit
        check_proximity(str(rand), str(user_input))