Untitled

<?php
session_start();
$userdaten = array( array('User', 'pass'), array('User2', 'pass2') );

if(isset($_SESSION["USER"]))
   exit("Hey ".$_SESSION["USER"]);

if(isset($_POST["username"]) && isset($_POST["pass"]) && !isset($_SESSION["USER"]))
{
   define('name', htmlspecialchars($_POST["username"]));
   define('pass', $_POST["pass"]);
   $error = null;

   foreach($userdaten as $user)
   {
       if($user[0] == name && $user[1] == pass)
       {
            $_SESSION["USER"] = name;
            header("Location: ");
       }
       else
           $error = "Die Zugangsdaten sind falsch.";
   }

   if($error != null)
      print('<font style="color: #FF0000">'.$error.'</font>');
}

?>
<html>
<head>
</head>
<body>
<form method="post">
<label>Username:&nbsp;<input type="text" name="username" /></label><br />
<label>Passwort:&nbsp;<input type="password" name="pass" /></label><br />
<input type="submit" value="Anmelden" />
</form>
</body>
</html>