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I've never had a the need to use a lookaround, but your question piqued my curiosity. As an experiment, I used Regexp::Assemble to rework your example because it just does the right thing with assertions, lookaheads, and lookbehinds.
#! /usr/bin/perl -slw use strict; use Regexp::Assemble; my $needs = Regexp::Assemble->new->add( qw[ FILE INFO ] ); my $has = Regexp::Assemble->new->add( qw[ FILE INFO SYSLOG ] ); while( defined( $_ = <DATA> )) { chomp; if( /($needs)/ ) { print $needs->as_string; } } while( defined( $_ = <DATA> )) { chomp; if( /($has)/ ) { print $has->as_string } } __DATA__ FILE INFO SYSLOG
I believe, if I"ve understood you correctly, that it works the way that it should. What do you think?

In reply to Re: regex: negative lookahead by Khen1950fx
in thread regex: negative lookahead by svenXY

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