A variation on listing all the files in a directory recursively. The code illustrates a basic technique : the use of an auxiliary function. It avoids building temporary lists which are merged on the way back. Note that the array which collects the information must be passed by reference.

<?php
function listdir($dir='.') {
    if (!is_dir($dir)) {
        return false;
    }
    
    $files = array();
    listdiraux($dir, $files);

    return $files;
}

function listdiraux($dir, &$files) {
    $handle = opendir($dir);
    while (($file = readdir($handle)) !== false) {
        if ($file == '.' || $file == '..') {
            continue;
        }
        $filepath = $dir == '.' ? $file : $dir . '/' . $file;
        if (is_link($filepath))
            continue;
        if (is_file($filepath))
            $files[] = $filepath;
        else if (is_dir($filepath))
            listdiraux($filepath, $files);
    }
    closedir($handle);
}

$files = listdir('.');
sort($files, SORT_LOCALE_STRING);

foreach ($files as $f) {
    echo  $f, "\n";
}
?>