CODEWITHSUNDEEP
pythonregex
that guy
that guy

Reputation: 404

Checking if regex returns None

Hi everyone I am doing the python challenge at pythonchallenge.com and i am currently at challenge 4. And I have the following code:

import urllib,re
number = 12345
url = 'http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=' + str(number)
page = urllib.urlopen(url)

def nextNumber(site):
    contents = page.read()
    decimal = re.search(r'\d+', contents).group()
    while decimal in contents and decimal: 
        new_url = 'http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=' +      str(decimal) 
        print new_url
        page2 = urllib.urlopen(new_url)
        contents = page2.read()
        decimal = re.search(r'\d+', contents).group()
nextNumber(url)

the problem I have is that when I get to the number 16044 the site says I have to divide it by two so decimal equals None and that gives an error. I tried to solve it with some if statements like:

if decimal is None:
    print "hi"

but I still get this error.

Upvotes: 0

Views: 296

Answers (1)

Eugen
Eugen

Reputation: 2370

Your problem is in this statement (in the while loop):

decimal = re.search(r'\d+', contents).group()

re.search returns None if no match was found.

Try this instead:

decimal = re.search(r'\d+', contents)
if decimal:
  decimal = decimal.group()
else:
  # do something else

Upvotes: 2

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