PHP lists the implementation code of all subdirectories in the directory

/**
* Remove all subdirectories of the specified directory
* edit: bbs.it-home.org
* 2013/10/9
*/
function listdir($dir){
 if ($handle = opendir($dir)){
 $output = array( );
 while (false !== ($item = readdir($handle))){
 if (is_dir($dir.'/'.$item) and $item != "." and $item != " .."){
 $output[] = $dir.'/'.$item;
 $output = array_merge($output, ListDescendantDirectories($dir.'/'.$item));
 }
 }
 closedir ($handle);
 return $output;
 }else{
 return false;
 }
}
//Call to get all subdirectories in the directory and loop through.
$dirs = listdir('myDirectory');
foreach($dirs as $dir){
 echo $dir.'';
}
?>