string compare question.Please Help!!!

[Don O'Donnell]

Evgeny Jonson wrote:
> 
> #For IP addres something like this:
> 
> import string
> import sys
> 
> def ip_cmp(ip1, ip2):
>     """Compare IP addreses as strings
>     """
>     l_ip1 = ip1.split('.')
>     l_ip2 = ip2.split('.')
>     if len(l_ip1) == 4 and len(l_ip2) == 4:
>         s_ip1 = string.zfill(l_ip1[0], 3) + '.' + \
>                 string.zfill(l_ip1[1], 3) + '.' + \
>                 string.zfill(l_ip1[2], 3) + '.' + \
>                 string.zfill(l_ip1[3], 3)
> 
>         s_ip2 = string.zfill(l_ip2[0], 3) + '.' + \
>                 string.zfill(l_ip2[1], 3) + '.' + \
>                 string.zfill(l_ip2[2], 3) + '.' + \
>                 string.zfill(l_ip2[3], 3)
>         resault = cmp(s_ip1, s_ip2)
>     else:
>         print 'Wrong IP addres format!'
>         sys.exit(0)
> 
>     return resault
> 
> # my test
> 
> print ip_cmp('10.66.73.78','10.0.0.0') # return 1
> print ip_cmp('10.66.73.78','10.255.255.255')  # return -1


The concept is right but the implementation is tiresome. 
There is no need to convert the list back to a string, 
just compare the two lists.

Here is a quicker way:

>>> def ipnumlist(ipstr):
        """Convert an ip address to a list of integers"""
	return [int(s) for s in ipstr.split('.')]

>>> cmp(ipnumlist('10.66.73.78'), ipnumlist('10.255.255.255'))
-1

And, if you want to package the compare into a function:

>>> def ipcmp(ip1, ip2):
	return cmp(ipnumlist(ip1), ipnumlist(ip2))

>>> ipcmp('10.66.73.78', '10.255.255.255')
-1
>>> ipcmp('10.66.73.78', '10.55.255.255')
1

Cheers,
Don