A python script to convert number into different decimal. use "num.py [NUM]". NUM could be 100, 0x100, 0b100

num.py

#!/usr/bin/python

import sys
import re

reHex = re.compile(r"0x[\da-fA-F]+$")   # match hex: 0x1100
reBin = re.compile(r"0b[01]+$") # match binary: 0b1100
reDec = re.compile(r"^\d+$")    # match deciman: 1100

def usage():
        print "\nusage:"
        print "\t" + sys.argv[0] + " <Num>"
        print "\t<num> could be 0x1100, 1100 or 0b1100\n"

'''
Split string into Array by length.
for seq='aaabbbccc', length=4
it returns ['aaab', 'bccc']
'''
def split_len(seq, length):
        return [seq[i:i+length] for i in range(0, len(seq), length)]

def split_and_join(word, prepend='', j='.', split=4):
        l = len(word)
        # when split=4, 'f' gap is 3, 'foo' gap is 1
        # 'foob' gap is 0. to know how many '0' to prepend.
        gap = (split - (l % split)) % split
        filled = word.zfill( l + gap)
        split = split_len(filled, split)
        return prepend + j.join(split)

def convert(word, decimal):
        print "[", word , "]"
        print "->\t", decimal,
        print "\t", split_and_join(hex(decimal)[2:],'0x'),
        print "\t", split_and_join(bin(decimal)[2:],'0b')
        print ""

def process(word):
        decimal = 0
        if reHex.match(word):
                decimal = int(word, 0)
        elif reBin.match(word):
                decimal = int(word, 2)
        elif reDec.match(word):
                decimal = int(word, 0)
        else:
                print "Not match: " + word
                print "should be '0x1100' '1100' or '0b1100'"
                return

        convert(word, decimal)

def untilExit():
        while 1:
                try:
                        line = sys.stdin.readline().strip('\r\n').split()
                except KeyboardInterrupt:
                        break
                if not line:
                        break
                for word in line:
                        process(word)

def go():
        for x in sys.argv[1:]:
                process(x)

if __name__ == "__main__":
        if len(sys.argv) > 1 and sys.argv[1] == '-h':
                usage()
        else:
                go()
                untilExit()