IP number conversion between dotnumber string and integer

What does the _ do in ipstring(_)?

In command line you get the last result from the last command from variable _, In my program I usually use _ to denote the return values, that I have no use for, for example when I do partition and are only interested the third part, which is after cutting:

Python 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]
Type "copyright", "credits" or "license" for more information.

IPython 0.10 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object'. ?object also works, ?? prints more.

In [1]: 2+3
Out[1]: 5

In [2]: _
Out[2]: 5

In [3]: a="Heikki Kovalainen, Finnish Formula 1 driver"

In [4]: _,_,prof=a.partition(',')

In [5]: prof
Out[5]: ' Finnish Formula 1 driver'

In [6]:

Doesn't look like Python at all!

That is IPython shell, which have much extra functionality, basically can give OS commands and Python commands both.

but same is applicable Idle, Python prompt etc.

And that double was same post again, but was no way to delete it even button EDIT/DELETE.

If you want to prove IPython, you can find it in http://ipython.scipy.org/moin/Download

Or you can do

python easy_install ipython

Hi,

You can optimize the ipnumber() function a bit with:

def ipnumber(ip):
    return reduce(lambda sum, chunk: sum <<8 | chunk, map(int, ip.split(".")))

This one month old newbie member did clear code by his standards (as old Lisper I do get the meaning of the code you posted, but it is not idiomatic Python). This senior poster would say:

def ipnumber(ip):
    return sum(256**power*int(value) for power, value in enumerate(reversed(ip.rstrip().split('.'))))
    
def ipstring(ip):
    return '.'.join('%s' % (ip // 256**ind  % 256) for ind in reversed(range(4)))

if __name__ == '__main__':
    testcase = '211.234.32.123'
    r = ipnumber(testcase)
    print('%s = %s = %s' % (testcase, r, ipstring(r)))

Yup, I must admit that the code snippet i cited is unreadable, and can be confusing. The reason I've decided to post it was a little provocation. You see, back then, when I was discovering beauty of Python, I saw this oneliner (although it was made to convert ethernet MAC address to long integer, not IP) and got inspired to learn reduce(), filter() and map() which are quite useful tools. Your code is much cleaner, but I just wanted to share some "ninja moves" I saw once :) Cheers.