#If you need compatibility with ancient versions of Python, you can either use gmpy 

#(which does include a fast, completely general int-to-string conversion function, and can 

#be built for such ancient versions – you may need to try older releases since the recent

#ones have not been tested for venerable Python and GMP releases, only somewhat recent ones)

#, or, for less speed but more convenience, use Python code – e.g., for Python 2, most 

#simply:

​

import string

digs = string.digits + string.ascii_letters

​

​

def int2base(x, base):

    if x < 0:

        sign = -1

    elif x == 0:

        return digs[0]

    else:

        sign = 1

​

    x *= sign

    digits = []

​

    while x:

        digits.append(digs[int(x % base)])

        x = int(x / base)

​

    if sign < 0:

        digits.append('-')

​

    digits.reverse()

​

    return ''.join(digits)

​

​

#For Python 3, int(x / base) leads to incorrect results, and must be changed to x // base:

​

import string

digs = string.digits + string.ascii_letters

​

​

def int2base(x, base):

    if x < 0:

        sign = -1

    elif x == 0:

        return digs[0]

    else:

        sign = 1

​

    x *= sign

    digits = []

​

    while x:

        digits.append(digs[x % base])

        x = x // base

​

    if sign < 0:

        digits.append('-')

​

    digits.reverse()

​

    return ''.join(digits)