open my $FH, '<', $file or die "Can't open $file: $!\n";

##</code><code>##

use Data::Dumper;

my @arr;
while (<DATA>) {
    chomp;
    push @arr, $1 if m{^ +\s+(//.*)};
}

print Dumper \@arr;

__DATA__
  // humpty dumpty
  // sat on a wall
-// eating her curds and whey
  // humpty dumpty
  // had a great fall

##</code><code>##

$VAR1 = [
          '// humpty dumpty',
          '// sat on a wall',
          '// humpty dumpty',
          '// had a great fall'
        ];