<?php?session_start();switch($_GET["action"])?{
????case?"login":
????????if?($_SERVER["REQUEST_METHOD"]?==?"POST")?{
????????????$user?=?(isset($_POST["user"])?&&
????????????????ctype_alnum($_POST["user"])???$_POST["user"]?:?null;
????????????$pass?=?(isset($_POST["pass"]))???$_POST["pass"]?:?null;
????????????$salt?=?'$2a$07$my.s3cr3t.SalTY.str1nG$';

????????????if?(isset($user,?$pass)?&&?(crypt($user?.?$pass,?$salt)?==
????????????????crypt("admintest",?$salt)))?{
????????????????$_SESSION["user"]?=?$_POST["user"];
????????????}
????????}
????????break;

????case?"logout":
????????$_SESSION?=?array();
????????session_destroy();
????????break;}header("Location:?login.php");?>

上面代碼運行時提示500錯誤，大家幫忙找下原因。