>perl -wMstrict -le
"my $line = 'Hello hello START this is comment END '
          . 'START this is still comment END '
          . 'START this should still be comment END '
          . 'this is fixed'
          ;
 ;;
 my $START   = qr{ START \s* \K }xms;
 my $END     = qr{ (?= \s* END) }xms;
 my $not_end = qr{ (?! $END) .  }xms;
 ;;
 my ($extract) =
   $line =~ m{ $START $not_end* should $not_end* $END }xmsg;
 print qq{[[$line]]};
 print qq{'$extract'};
"
[[Hello hello START this is comment END START this is still comment
END START this should still be comment END this is fixed]]
'this should still be comment'

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In reply to Re: extract a substring between two emements by AnomalousMonk
in thread extract a substring between two emements by Shaveta_Chawla

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