Dear Monks, I would to know why the following regexp: 
use strict;
use warnings FATAL => 'all';
 
my $string = "aacbbbcac";
 
my $re1 = qr/((a+)?(b+)?(c))*/;
if ($string =~ $re1) {
  foreach (0..$#-) {
    printf "Group %d: <%s>\n", $_, substr($string, $-[$_], $+[$_] - $-
+[$_]);
  }
}

[download]
produces this result: 
Group 0: <aacbbbcac>
Group 1: <ac>
Group 2: <a>
Group 3: <bbb>
Group 4: <c>

[download]
i.e. $3 is not empty.

Guessing this is normal, may I ask also if it is possible, with the same regexp, to get a coherent result i.e. $1 equal to $something2.$something3.$something4 ?

ps: some readers may find that I also posted this question to google perl community. I want to keep the original regexp as is. Note that I envisaged to do to perlreapi it this is impossible to have $3 empty with standard perl - if perlreapi permits this manipulation (!?)

In reply to Explain a regexp matched group result by jdd

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