use File::Find;

my $total_size = 0;
find(sub {$total_size += -s if -f}, '.');
print $total_size, "\n";

##</code><code>##

use File::Find;
my $callback;
{
  my $count = 0;
  $callback = sub { print ++$count, ":$File::Find::name\n" };
}
find($callback, '.');