Python's regular expression help

[MRAB]

goldtech wrote:
> Hi,
> Trying to start out with simple things but apparently there's some
> basics I need help with. This works OK:
>>>> import re
>>>> p = re.compile('(ab*)(sss)')
>>>> m = p.match( 'absss' )
>>>> m.group(0)
> 'absss'
>>>> m.group(1)
> 'ab'
>>>> m.group(2)
> 'sss'
> ...
> But two questions:
> 
> How can I operate a regex on a string variable?
> I'm doing something wrong here:
> 
>>>> f=r'abss'
>>>> f
> 'abss'
>>>> m = p.match( f )
>>>> m.group(0)
> Traceback (most recent call last):
>   File "<pyshell#15>", line 1, in <module>
>     m.group(0)
> AttributeError: 'NoneType' object has no attribute 'group'
> 
Look closely: the regex contains 3 letter 's', but the string referred
to by f has only 2.

> How do I implement a regex on a multiline string?  I thought this
> might work but there's problem:
> 
>>>> p = re.compile('(ab*)(sss)', re.S)
>>>> m = p.match( 'ab\nsss' )
>>>> m.group(0)
> Traceback (most recent call last):
>   File "<pyshell#26>", line 1, in <module>
>     m.group(0)
> AttributeError: 'NoneType' object has no attribute 'group'
> 
> Thanks for the newbie regex help, Lee

The string contains a newline between the 'b' and the 's', but the regex
isn't expecting any newline (or any other character) between the 'b' and
the 's', hence no match.