How to move a folder with files and folders to another folder?

Question

PHP

Good morning everyone! I have this code

$old_dir = 'test/gg'; 
 $new_dir = 'kl/gg'; 
 
 mkdir($new_dir, 0755); 
 $dir = opendir($old_dir); 
 while($file = readdir($dir)) 
 { 
 if(is_file($old_dir."/".$file)) 
 { 
 $cont = file_get_contents($old_dir."/".$file); 
 file_put_contents($new_dir."/".$file, $cont); 
 } 
 }

The joke is that it only creates a folder, but it does not transfer files and folders, used copy, it still does not help.

I used several codes that I found on the Internet, they used copy but they still only transfer files too.

Does anyone have their own function? I will be grateful for your function :)

Here is the code from the Internet

# Папка с файлами
$old_dir = './kap/';
 
# Папка в которую перемещаем
$new_dir = './bridun/';
 
$dir=opendir($old_dir);
$i=1;
while (false !== ($file = readdir($dir))) {
    if (is_file($old_dir.$file ) && $file[0] != '...') 

  {
        if (!file_exists($new_dir.$file[0])) {
            #Создаём папку по первому символу от названия
           mkdir($new_dir.$file[0], 0755); #0777
       }
        copy($old_dir.$file, $new_dir.$file[0].'./'.$file);
    }
    #Ограничиваем за один раз
   if ($i==500) break;
    $i++;
}
closedir($dir);

As I wrote at the top that it does not transfer folders, only files