replace frames in php

[BlackMagic]

a buddy told me to use this..

<?php 
if (!isset($_GET["link"])) include 'main.php';
else if(is_file($_GET["link"] . ".php") && $_GET["link"] !="index" ) include htmlspecialchars($_GET["link"] . ".php");
else include 'error.php';
?>

seems to work how i wanted