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Re^3: RegEx Matching, Loop Breaking...

by AnomalousMonk (Monsignor)
on May 28, 2013 at 20:05 UTC ( #1035715=note: print w/ replies, xml ) Need Help??


in reply to Re^2: RegEx Matching, Loop Breaking...
in thread RegEx Matching, Loop Breaking...

The reason taking the quotemeta out fixed the problem is that a quotemeta-ed string that contained  \W characters will, in general (there may be some oddball corner cases), not regex-match with itself after the string has been double-quote-ishly interpolated into a regex. The reason is that after a string is quotemeta-ed, something like  '\-' in the quotemeta-ed string is literally a backslash-hyphen sequence of characters, but this sequence in a regex only matches a hyphen leaving the backslash in the quotemeta-ed string unmatched.

>perl -wMstrict -le "my $s = 'a-b c*d'; my $qm_s = quotemeta $s; print qq{raw: '$s' quotemeta-ed: '$qm_s'}; ;; printf qq{%s equal \n}, $qm_s eq $qm_s ? '' : 'NOT '; printf qq{%s match \n}, $qm_s =~ /$qm_s/ ? '' : 'NO '; " raw: 'a-b c*d' quotemeta-ed: 'a\-b\ c\*d' equal NO match


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