real noob problem . .

[deeq]

Hi I foud this code:

<?
$path = "/home/sites/site50/web/";


//////////////////    Open the folder


$dir = @opendir($path) or die("Kan de directory $path Niet openen");


//////////////////    Loop through the files


 while ($file = readdir($dir))

{
	if($file == "." || $file == ".." || $file == "indexer2.php" )

   	 continue;


    	echo "<a href=\"$file\">$file</a><br />";

}

///////////////////// Close

closedir($dir);

?>

This wil output the directory as a link, how can I exculde certain files like .html or .php and prefixes of file names like TN_image01.jpg can anyone complete this code and give me some explanation?
Thanks A Lot,
Deeq

[Installer]

// Array of strings that "disqualify" files.
$excluded = array('indexer2.php', '.html', '.php', 'TN_');
// Read the directory.
while ($file = readdir($dir)) {
    // echo by default.
    $echo_file = true;
    // Loop through unwanted strings.
    foreach ($excluded as $value) {
        // Check each file for unwanted string; strtolower() covers all.
        if  (strpos(strtolower($file), strtolower($value)) !== false) {
            // If unwanted string found, don't echo the file.
            $echo_file = false;
            // One false is all we need.
            break;
        }
    }
    // Now check to see if the file is flagged, etc.
    if (($echo_file != false) && ($file != '.') && ($file != '..')) {
        // If everything is ok, echo the file.
        echo '<a href="' . $file . '">' . $file . '</a><br />';
    }
}