is it possible to do Math on Variable Values in Regex?

Question

i am wondering of it is possible to do some simple Math on RegEx Variable values. E.G.:

I am looking for all two-digit numbers is a textfile and would like to multiply them by 10. Is simple regex able to do this or do i need to use a more complex script for that?

thanks!

Really a bad idea to do math on regex – Srini V Nov 11 '13 at 13:28 — Srini V, Nov 11 '13 at 13:28

falsetru · Accepted Answer · 2013-11-11T14:58:24.183

3

Multiply two-digits number is like appending 0 at the end of the numbers. So that can be done with any regular expression that support replace and capturing group.

For example, here is Python code:

>>> re.sub(r'\b(\d{2})\b', r'\g<1>0', 'There are 10 apples.')
'There are 100 apples.'

But what you want is multiply by arbitrary number, then you need the regular expression engine that support some kind of callback / evaluation.

>>> re.sub(r'\b(\d{2})\b', lambda m: str(int(m.group(1)) * 5), '10 apples.')
'50 apples.'

edited Nov 11 '13 at 14:58

answered Nov 11 '13 at 13:25

falsetru

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thanks, of course the latter is what i wanted, multiply by 10 was just an example ;) – zantafio Nov 11 '13 at 13:56

is it possible to do Math on Variable Values in Regex?

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