<?php

   // simple juste use FilesystemIterator 
   // and you can skip dot and duble dot
   // and use it in array
   // new FilesystemIterator( PATH , OPTIONS ) : array 

$array_file_list = new FilesystemIterator( PATH_ROOT . 'folder/', FilesystemIterator::SKIP_DOTS );

?>

This one's pretty nice.  After getting frustrated for hunting down .jpg files in my massive music collection (PHP would run out of memory), I thought there should be a preg_ls function.

function preg_ls ($path=".", $rec=false, $pat="/.*/") {
    // it's going to be used repeatedly, ensure we compile it for speed.
    $pat=preg_replace("|(/.*/[^S]*)|s", "\\1S", $pat);
    //Remove trailing slashes from path
    while (substr($path,-1,1)=="/") $path=substr($path,0,-1);
    //also, make sure that $path is a directory and repair any screwups
    if (!is_dir($path)) $path=dirname($path);
    //assert either truth or falsehoold of $rec, allow no scalars to mean truth
    if ($rec!==true) $rec=false;
    //get a directory handle
    $d=dir($path);
    //initialise the output array
    $ret=Array();
    //loop, reading until there's no more to read
    while (false!==($e=$d->read())) {
        //Ignore parent- and self-links
        if (($e==".")||($e=="..")) continue;
        //If we're working recursively and it's a directory, grab and merge
        if ($rec && is_dir($path."/".$e)) {
            $ret=array_merge($ret,preg_ls($path."/".$e,$rec,$pat));
            continue;
        }
        //If it don't match, exclude it
        if (!preg_match($pat,$e)) continue;
        //In all other cases, add it to the output array
        $ret[]=$path."/".$e;
    }
    //finally, return the array
    return $ret;
}

Not bad for a mere 18 lines, don't you think?

Example use:

foreach (preg_ls("/etc/X11", true, "/.*\.conf/i") as $file) echo $file."\n";

Output: 

/etc/X11/xkb/README.config
/etc/X11/xorg.conf-vesa
/etc/X11/xorg.conf~
/etc/X11/gui.conf
/etc/X11/xorg.conf
/etc/X11/xorg.conf-fbdev

Note that the dir object will use the default encoding for non-unicode programs on Windows with PHP 5.x.

So, if you have a file named with characters unsupported by the current default encoding, the dir->read() method will return a wrong entry.

<?php
/*
** This script is on the same directory than a file named with
** unsupported characters for the current default encoding.
*/
$d = dir("./");
while(false !== ($e = $d->read()))
    echo $e . '<br/>';
?>

This will print a "?" for every unsupported characters, and not the right file name. So take care if you check with is_file/is_dir right after enumerating.

<?php

/*
  New recursive PHP8 
  gen array path with  FilesystemIterator
*/

$recurcive_path = [];
rdir(path, $recurcive_path);
var_dump($recurcive_path);

function rdir(string $path, array &$recurcive_path): string
{
    if ($path != '') {
        $recurcive_path[] = $path;
        $array_list = iterator_to_array(new FilesystemIterator($path, FilesystemIterator::SKIP_DOTS));
        foreach ($array_list as $name) {
            $pathname = $name->getpathname();
            if(is_dir($pathname) && $name->getfilename()[0] != '.'){
                $path = rdir($pathname,$recurcive_path);
            }
        }
        return $path;
    }
    return '';
}

?>

Regarding samuel's comment about the dir() function not supporting Unicode properly, it's all in the encoding. The function does NOT internally change Unicode characters into question marks (?), as I was first led to believe. If you simply try to output them in UTF-8, they'll show up just right.

to get a dir of http://www.example.com/directory

<?php
function remotedir($dir)
{
  $dir = str_replace(" ", "%20", html_entity_decode($dir));
  if (($rh = fopen($dir, 'rb')) === FALSE) { return false; }
  $i = 0;
  while (!feof($rh)) {
     $archivos = fgetss($rh);
     $directorio[$i++] = trim( substr($archivos,1,strpos($archivos," ",1)) );
  }
  fclose($rh);
  return $directorio;
}
?>