Different types of regular expression testers

Asked Jan 26 '16 at 04:56

Active Jan 27 '16 at 04:38

Viewed 71 times

I am testing an Rstudio regex on regex101.com: ([0-9]+([+\\-\\*\/]+[0-9]+){1,}) works fine with my test data:

1/3
1+2
1/3
10*2
10*8/3

However when I put that regex into Rstudio it freaks out because \/ is not a valid escape character (but this was required for the regex101.com to work)

What is the difference between the ways regex is being evaluated in the two programs?

Justification for re-opening:

This question is not intended to deal with a specific regex (I included the one above just as an example).

I have never see an answer to the actual question asked in this post. Although there are many specific regex questions this is intended to be more of a general difference between regex types question (eg Perl regex vs Notepad++).

edited Jan 27 '16 at 04:38

asked Jan 26 '16 at 04:56

Rilcon42

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2

use this `([0-9]+([+\\-\\*/]+[0-9]+){1,})`, In R, yu just need to double escape the backslash. – Avinash Raj Jan 26 '16 at 04:57
3

In addition, speaking of differences: if you want to use pcre regexes, which is the default on regex101.com, you may want to set `perl=TRUE` in `grep` or `sub` or whatever you use in R. – lukeA Jan 26 '16 at 07:32
1

I think this is a good question exposing the backslashing issue and should not be considered a mere typo. – Roman Luštrik Jan 26 '16 at 08:32
@RomanLuštrik: Then please hit *Reopen*. – Wiktor Stribiżew Jan 26 '16 at 08:51

Different types of regular expression testers

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