Robert Dailey wrote:
On Aug 6, 11:02 am, MRAB <pyt...@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!
By 'special' I mean ones like '?', '*', '(', etc. ',' isn't special in
that sense.
In fact, the {...} quantifier is special only if it's syntactically
correct, otherwise it's just a literal, eg "a{," and a{} are just
literals.
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