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Postings from April 2008
On Wed, Apr 30, 2008 at 04:49:03PM +0200, Bram wrote:
> Quoting James Mcclure <perlbug-followup@perl.org>:
> >
> ># perl zero-length regex bug
> >
> ># instructions:
> ># 1) run with $ARGV[0] = 1, this script prints false
> ># 2) run with $ARGV[0] = 2, this script prints true
> ># 3) comment out the $ARGV[0] =~ /1/ line --> this script prints true
> >$ARGV[0] =~ /1/;
> >if ( '' =~ // ) { print "true\n"; }
> >else { print "false\n"; }
> >
> >-----------------------------------------------------------------
>
> Hello,
>
> Thank you for your bug report but this is not a bug.
>
>
> If you use an empty pattern after a re then it uses the pattern of the
> last succesful match.
>
> It is mentioned in
> http://perldoc.perl.org/perlretut.html#Using-regular-expressions-in-Perl
>
>
> But perhaps it could/should be documented more clearly... (I can't
> easily find it in perlre for example - or atleast not using a basic
> search)
From perlop:
If the PATTERN evaluates to the empty string, the last success-
fully matched regular expression is used instead. In this case,
only the "g" and "c" flags on the empty pattern is honoured -
the other flags are taken from the original pattern. If no
match has previously succeeded, this will (silently) act
instead as a genuine empty pattern (which will always match).
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