binary_decimal.py

"""
Binary to Decimal and Back Converter
Develop a converter to convert a decimal number to binary
or a binary number to its decimal equivalent.
"""

def binary_to_decimal(binary):
    """
    Converts a binary number into a decimal number.
    """
    decimal = 0
    index = 0
    while binary > 0:
        last = binary % 10
        binary = binary / 10
        decimal += (last * (2 ** index))
        index += 1
    return decimal

def decimal_to_binary(decimal):
    """
    Converts a decimal number into a binary number.
    """
    binary = ""
    remainders = []
    while decimal > 0:
        remainders.append(str(decimal % 2))
        decimal /= 2
    remainders.reverse()
    binary = "".join(remainders)
    return binary

if __name__ == '__main__':
    print """
    1. Binary to Decimal
    2. Decimal to Binary\n
    """

    choice = input("Make a choice: ")

    if choice == 1:
        binary = input("Binary to convert: ")
        print "The binary number %d in decimal is %d" % \
              (binary, binary_to_decimal(binary))
    elif choice == 2:
        decimal = input("Decimal to convert: ")
        print "The decimal number %d in binary is %s" % \
              (decimal, decimal_to_binary(decimal))
    else:
        print "Invalid choice"