[Tutor] Regular expression - I

[Santosh Kumar]

Steve,

i am trying to under r - raw string notation. Am i understanding it wrong.
Rather than using "\", it says we can use the "r" option.

http://docs.python.org/2/library/re.html

Check the first paragraph for the above link.

Thanks,
santosh



On Tue, Feb 18, 2014 at 11:33 PM, Steve Willoughby <steve at alchemy.com>wrote:

> Because the regular expression <H*> means “match an angle-bracket
> character, zero or more H characters, followed by a close angle-bracket
> character” and your string does not match that pattern.
>
> This is why it’s best to check that the match succeeded before going ahead
> to call group() on the result (since in this case there is no result).
>
>
> On 18-Feb-2014, at 09:52, Santosh Kumar <rhce.san at gmail.com> wrote:
>
> >
> > Hi All,
> >
> > If you notice the below example, case I is working as expected.
> >
> > Case I:
> > In [41]: string = "<H*>test<H*>"
> >
> > In [42]: re.match('<H\*>',string).group()
> > Out[42]: '<H*>'
> >
> > But why is the raw string 'r' not working as expected ?
> >
> > Case II:
> >
> > In [43]: re.match(r'<H*>',string).group()
> >
> ---------------------------------------------------------------------------
> > AttributeError                            Traceback (most recent call
> last)
> > <ipython-input-43-d66b47f01f1c> in <module>()
> > ----> 1 re.match(r'<H*>',string).group()
> >
> > AttributeError: 'NoneType' object has no attribute 'group'
> >
> > In [44]: re.match(r'<H*>',string)
> >
> >
> >
> > Thanks,
> > santosh
> >
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>


-- 
D. Santosh Kumar
RHCE | SCSA
+91-9703206361


Every task has a unpleasant side .. But you must focus on the end result
you are producing.
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