PERL Regex Negation Issue

Question

I have written a regex to pick files of the format (ABC.*\.DAT) in perl.

How to write a negation for the above regex?

I already tried expressions like (?!ABC.*)\.DAT or (?!(ABC.*\.DAT))

Any help is appreciated.

Why don't you simply use `!~` instead of `~` as the regex application operator? — Jonathan Leffler, Apr 14 '15 at 06:45
@BhargavModi question is unclear for me. I think he wants this `^(?!ABC.*\.DAT$).*\.DAT$` — Avinash Raj, Apr 14 '15 at 06:46
@AvinashRaj I meant I don't want to match any files matched by '(ABC.*\.DAT)' — maverick_27, Apr 14 '15 at 06:49

score 1 · Accepted Answer · edited Apr 14 '15 at 16:48

1

(?s:(?!ABC).)*\.DAT

You can try this negation based regex. See demo.

The above can be safely embedded into a larger pattern. For example,

/^(?:(?!ABC).)*\.DAT\z/s

If you are trying to match the whole input, and if ABC doesn't end with ., .D, .DA or .DAT, then the following will be faster:

/^(?!.*ABC)\.DAT\z/s

edited Apr 14 '15 at 16:48

ikegami

answered Apr 14 '15 at 06:46

vks

@maverick_27 did you want to allow `ABC` at the middle? – Avinash Raj Apr 14 '15 at 06:59
Nope..it shouldn't allow the pattern ABC in the filename.... I tested that too... – maverick_27 Apr 14 '15 at 07:01
@maverick_27 `^(?!.*ABC).*\.DAT$` – Avinash Raj Apr 14 '15 at 07:03
@AvinashRaj will test that and get back to you – maverick_27 Apr 14 '15 at 07:13

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