How can I use PHP to check if a directory is empty?

I think using the FilesystemIterator should be the fastest and easiest way:

// PHP 5 >= 5.3.0
$iterator = new \FilesystemIterator($dir);
$isDirEmpty = !$iterator->valid();

Or using class member access on instantiation:

// PHP 5 >= 5.4.0
$isDirEmpty = !(new \FilesystemIterator($dir))->valid();

This works because a new FilesystemIterator will initially point to the first file in the folder - if there are no files in the folder, valid() will return false. (see documentation here.)

As pointed out by abdulmanov.ilmir, optionally check if the directory exists before using the FileSystemIterator because otherwise it'll throw an UnexpectedValueException.

I found a quick solution

<?php
  $dir = 'directory'; // dir path assign here
  echo (count(glob("$dir/*")) === 0) ? 'Empty' : 'Not empty';
?>

It seems that you need scandir instead of glob, as glob can't see unix hidden files.

<?php
$pid = basename($_GET["prodref"]); //let's sanitize it a bit
$dir = "/assets/$pid/v";

if (is_dir_empty($dir)) {
  echo "the folder is empty"; 
}else{
  echo "the folder is NOT empty";
}

function is_dir_empty($dir) {
  if (!is_readable($dir)) return null; 
  return (count(scandir($dir)) == 2);
}
?>

Note that this code is not the summit of efficiency, as it's unnecessary to read all the files only to tell if directory is empty. So, the better version would be

function dir_is_empty($dir) {
  $handle = opendir($dir);
  while (false !== ($entry = readdir($handle))) {
    if ($entry != "." && $entry != "..") {
      closedir($handle);
      return false;
    }
  }
  closedir($handle);
  return true;
}

By the way, do not use words to substitute boolean values. The very purpose of the latter is to tell you if something empty or not. An

a === b

expression already returns Empty or Non Empty in terms of programming language, false or true respectively - so, you can use the very result in control structures like IF() without any intermediate values