PHP Rename filenames to numbers

Rename filenames to numbers

<?
$dir = "test";
$handle = opendir($dir);
while($file = readdir($handle)) {
  if ($file != "." && $file != ".." && !is_dir("$dir/$file")) {
    $sbor = $sbor+1;
    $part = explode(".",$file);
    $ext = $part[count($part)-1];
    rename("$dir/$file","$dir/$sbor.$ext");
  }
}
?>