<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="get">
    <input type="text" name="user" value=""><br />
    <input type="password" name="pass" value=""><br />
    <input type="text" name="code" value=""><br />
    accept<br />
    <input type="submit" ><br />
    </form>

<?php
$codearr = array(123, 321);
        if ($user == "He" && $pass=="abcd" && in_array($code,$codearr)){

            echo "OK <br />";
           }
           else{

           echo "Wrong <br />";
    ?>