PHP求助～～

<?php
include"inc/ubb.php";
$id=$_get["id"];
if($id=""){
$html=fopen("html/index.php","r") or exit("打开页面失败!");
}eles{
$html=fopen("html/$id.php","r") or exit("打开页面失败!");
}
echo $nr;
?>

$str = preg_replace("/\[xz=(.*)\](.*)\[\/xz\]/iUs", "<a href='\\1'>\\2</a>", $str);