Help with regex

Robert Dailey rcdailey at gmail.com
Thu Aug 6 18:17:10 CEST 2009


On Aug 6, 11:02 am, MRAB <pyt... at mrabarnett.plus.com> wrote:
> Robert Dailey wrote:
> > Hey guys,
>
> > I'm creating a python script that is going to try to search a text
> > file for any text that matches my regular expression. The thing it is
> > looking for is:
>
> > FILEVERSION #,#,#,#
>
> > The # symbol represents any number that can be any length 1 or
> > greater. Example:
>
> > FILEVERSION 1,45,10082,3
>
> > The regex should only match the exact above. So far here's what I have
> > come up with:
>
> > re.compile( r'FILEVERSION (?:[0-9]+\,){3}[0-9]+' )
>
> > This works, but I was hoping for something a bit cleaner. I'm having
> > to create a special case portion of the regex for the last of the 4
> > numbers simply because it doesn't end with a comma like the first 3.
> > Is there a better, more compact, way to write this regex?
>
> The character class \d is equivalent to [0-9], and ',' isn't a special
> character so it doesn't need to be escaped:
>
>      re.compile(r'FILEVERSION (?:\d+,){3}\d+')

But ',' is a special symbol It's used in this way:
{0,3}

This will match the previous regex 0-3 times. Are you sure commas need
not be escaped?

In any case, your suggestions help to clean it up a bit!



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