Base62 encode/decode tools (convert number to string)

base62.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-
# Base62 tools (convert number <=> string)
# v1.0/20130109
# python 2.x/3.x supported
#
#author: Ady Liu([email protected])
#github: github.com/adyliu

import sys

basedigits='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
BASE=len(basedigits)


def decode(s):
    ret,mult = 0,1
    for c in reversed(s):
        ret += mult*basedigits.index(c)
        mult *= BASE
    return ret

def encode(num):
    if num <0: raise Exception("positive number "+num)
    if num ==0: return '0'
    ret=''
    while num != 0:
        ret = (basedigits[num%BASE])+ret
        num = int(num/BASE)
    return ret


if __name__ == '__main__':
    if len(sys.argv) < 2:
        print("Usage: base62.py <num>...")
        sys.exit(1)
    width = max(len(x) for x in sys.argv[1:])
    for argv in sys.argv[1:]:
        try:
            num = int(argv)
            print('%*s %s %s' % (width,argv,'ENCODE',encode(num)))
        except ValueError:
            print('%*s %s %s' % (width,argv,'DECODE',decode(argv)))

demo.sh

adylab:bin adyliu$ python base62.py 16075652386131968 1bCQSgeUyk
16075652386131968 ENCODE 1bCQSgeUyk
       1bCQSgeUyk DECODE 16075652386131968
adylab:bin adyliu$ python3 base62.py 16075652386131968 1bCQSgeUyk
16075652386131968 ENCODE 1bCQSgeUyk
       1bCQSgeUyk DECODE 16075652386131968