Nick Ku- URL

"""url.py by Nick Ku"""

def number_to_character( number ):
#Note: <10: 0-9, 10-35: A-Z, 36-61: a-z, 62: -, 63: +, reject out of range
    if number < 10:
        return chr( number + 48)
    elif 10 <= number <= 35:
        return chr( number + 55 )
    elif 35 < number <= 61:
        return chr( number + 61 )
    elif number == 62:
        return chr( 45 )
    elif number == 63:
        return chr( 43 )
    else:
        print ('Invalid number')

def character_to_number( character ):
#Note: Inverse function. Transform letter to its order then subtract.
    number = ord( character )
    if 48 <= number <= 57:
        return number-48
    elif 65 <= number <= 90:
        return number - 55
    elif 97 <= number <= 122:
        return number - 61
    elif number == 45:
        return 62
    elif number == 43:
        return 63
    else:
        print ('Invalid character')

def encode( number ):
#converts number into 6 characters, must convert into base 64 first
    new_number = ""
    if number < 0:
        print ('Negative numbers are invalid')
    while number !=0:
        remainder = number % 64
        new_number += number_to_character(remainder)
        number //= 64
    while len(new_number) < 6:
        new_number += '0'
    new_number = new_number[:6]
    return new_number

def decode( number ):
#inverse of encode
    result = 0
    exponent = 0
    for item in number:
        result += character_to_number(item) * (64**exponent)
        exponent += 1
    return result