php getUser php handle opendir while false file readdir handle if preg

<?php
//getUser.php
$handle = opendir('.');
while (false !== ($file = readdir($handle)))
	if(preg_match('/\.txt$/', $file) && file_get_contents($file) == $_GET['key']) {
		die(reset(explode('.', $file)));
        break;
    }
closedir($handle);
die('err');