<?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.

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.

<?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 '';
}

?>

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;
}
?>