sub DoStuff {
  my ($a, $b, $c) = (-1, -2, -3);
  if ($#_ == 2) {
    ($a, $b, $c) = @_;
  } elsif ($#_ == 1) {
    ($a, $c) = @_;
  } elsif ($#_ == 0) {
    ($b) = @_;
  };

  print "A= $a\n";
  print "B= $b\n";
  print "C= $c\n";
}


##</code><code>##


sub DoStuff {
  my ($a, $b, $c) = @_;
  $a = defined $a ? $a : -1;
  $b = defined $b ? $b : -2;
  $c = defined $c ? $c : -3;

  print "A= $a\n";
  print "B= $b\n";
  print "C= $c\n";
}