Script conta numero di file in una directory

<?php
class files
{
	private function check_ext($file, $correct)
	{
		$exp = explode('.', $file);
		$exp = $exp[count($exp) - 1];

		if($exp != $correct)
			return false;
		return true;
	}

	function count_files($directory, $extension)
	{
		if(!is_dir($directory))
			die('La directory scelta è inesistente.');

		$op = opendir($directory);
		$count = 0;

		while(false !== ($read = readdir($op)))
		{
			if($read == '.' || $read == '..')
				continue;

			if(is_dir("{$directory}/{$read}"))
				$count += $this->count_files("{$directory}/{$read}", $extension);
			elseif(file_exists("{$directory}/{$read}") && $this->check_ext($read, $extension))
				$count += 1;
		}

		closedir($op);
		return $count;
	}
}
?>

<?php
$f = new files();
echo $f->count_files('test');
?>