How to turn string to int with with characters within it?

Question

I'm building a simple email verifier and I need to know how to turn an ip address string into ints. I need (example Ip address) [a.b.c.d] to all be their own integer so that I may see if each is in the range of 0-255. The problem is that there are dots that separate them and I don't know how to just convert the individual sections.

I've never seen anyone use email addresses that are numeric ip addresses. Well, I'll admit to using `root@127.0.0.1` on a few sites... to sign up for their spam. Good filters will try to catch this sort of thing. — Paul, Jan 28 '15 at 01:21
@Paul It's true that you never really see this but you still could do this, I considered this possibility before — jamylak, Jan 28 '15 at 01:42
possible duplicate of [How to validate IP address in Python?](http://stackoverflow.com/questions/319279/how-to-validate-ip-address-in-python) — JCotton, Jan 28 '15 at 04:09

score 1 · Answer 1 · answered Jan 28 '15 at 01:32

As Charles Duffy suggested in the comments, the string.split() method will split a string into several substrings, returning a list of all substrings.

If you want to split at each 'dot', then use string.split('.'), otherwise it will split at whitespace.

For example:

address = ['10.1.0.1']
address_split = address.split('.')

lqhcpsgbl · Accepted Answer · 2015-01-28T01:54:58.980

What you need is to use the split method of string and judge every number is between [0,255]:

>>> a = '127.0.0.1'
>>> all(map(lambda a : 0 <= a <= 255, [int(i) for i in a.split('.')]))
True
>>> b = '256.1.2.3'
>>> all(map(lambda a : 0 <= a <= 255, [int(i) for i in b.split('.')]))
False

First use split() to get every part of an IP address and you get a list:

>>> a = '127.0.0.1'
>>> alist = a.split('.')
>>> alist
['127', '0', '0', '1']

Now, use list comprehension to get the number of of a alsit:

>>> num_list = [int(i) for i in alist]
>>> num_list
[127, 0, 0, 1]

I don't use try except the ValueError cause your input is IP, if not you can follow other answer.

Then, use map to judge if every number in num_list is in [0,255], it take an anonymous function and the list you want to judge. It return the bool value of every result of the element in num_list by judged the anonymous function:

>>> map(lambda num: 0 <= num <= 255, num_list)
[True, True, True, True]

Last, try all() function it will return True if all element in a list is True, otherwise False:

>>> all(map(lambda num: 0 <= num <= 255, num_list))
True

I believe this is what I need. Can you explain how each part of it works? — Crunch, Jan 28 '15 at 01:45
I really love you for this :) Thanks for the awesome explanation as well! — Crunch, Jan 28 '15 at 02:24

score 0 · Answer 3 · answered Jan 28 '15 at 01:43

Building slightly on Andrew Guy's suggestion:

try:
    address_octets = [int(x) for x in address.split('.')]
except ValueError, e:
    pass
    # fallback from the assumption that it's an IPv4 string
    # (Whatever that means for your code)
assert len(address_octets) == 4
    # (or use a conditional and fallback as described above)

... note that I have no idea how you'll want to handle the parsing failures and I'm not entirely sure that the only exception you could get would be ValueError.

How to turn string to int with with characters within it?

3 Answers3