[BangPypers] A trivial doubt in negative lookbehind regular expression pattern

[Neha Jain]

thanks senthil for the prompt reply..

On Tue, Apr 5, 2011 at 5:38 PM, Senthil Kumaran <orsenthil at gmail.com> wrote:

> On Tue, Apr 05, 2011 at 05:04:38PM +0530, Neha Jain wrote:
> > I am trying to avoid matching of the terms that start with a word ABC_
> > The general pattern is that the term has only caps alphabets and _, I
> have
> > to ignore from these terms, ones that begin in ABC_
> > The regular expression I have written is:
> >
> > pattern = re.compile( ' ((?<!ABC_)([A-Z_]+) )' )
>
> That is because your [A-Z_]+ will match the entire string and then it
> the string does not start with ABC_ is still true.
>
> How about using negative lookahead match at the start, by doing
> something like this.
>
> >>> m = re.search('^(?!ABC_)[A-Z_]+','ABC_CDF')
> >>> m.group(0)
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> AttributeError: 'NoneType' object has no attribute 'group'
> >>> m = re.search('^(?!ABC_)[A-Z_]+','AB_CDF')
> >>> m.group(0)
> 'AB_CDF'
>
>
but the problem with this is that the line where I am searching for may be
like..  #define ABC_PG... so may be something for the start of the word type
matching may help.. \b?? i am not sure..

Any pointers..?

> --
> Senthil
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-- 
Smiles
Neha )))))