create directory using loop with desired name

$ext = pathinfo($filename, PATHINFO_EXTENSION);
// get file extention in php
// List sub directories in a directory - dirname only
$demo_dirs_in_dir = array();
$demo_dirs_in_dir_temp = glob($_SERVER['DOCUMENT_ROOT']."/demo/*", GLOB_ONLYDIR);
foreach ($demo_dirs_in_dir_temp as $file) {
$demo_dirs_in_dir[] = pathinfo($file, PATHINFO_FILENAME);
}
$startTime = strtotime("tomorrow");
$i = 0;
$result = false;
while(!$result)
{
$dir_name = date("Ymd", strtotime('-'.$i++.' days', $startTime) );
if(!file_exists($dir_name))
{
$result = mkdir($dir_name, 0777, true);
}
if($i>100) break;
// do not iterate more then 100 times, even if not succeed.
}
echo "Created directory ". $dir_name;