PHP Formulario de Registro

<?php

require_once "connect.php";

$checkerr = array("");

//check the email, password, etc.

$email = $_POST["email"];
$name = $_POST["name"];
$pass = $_POST["password"];
$passval = $_POST["passwordval"];

if (filter_var($email, FILTER_VALIDATE_EMAIL) == false) {
    $checkerr[] = "The email you entered is not valid.";
} elseif (strlen($name) < 4) {
    $checkerr[] = "Your username must be more than 4 characters in length.";
} elseif (strlen($pass) < 6) {
    $checkerr[] = "Your password must be more than 6 characters in length.";
} elseif ($pass != $passval) {
    $checkerr[] = "The two passwords you entered do not match.";
}

//code that generates an id

$filename = 'genid.txt';
$handle = fopen($filename, 'r');

if (flock($handle, LOCK_SH)) {
    $genid = trim(fgets($handle)) + 1;
    flock($handle, LOCK_UN);
} else {
    $checkerr[] = "flock() failed. Contact me.";
}

fclose($handle);

$handle = fopen($filename, 'w');

if (flock($handle, LOCK_EX)) {
    fwrite($handle, $genid);
    flock($handle, LOCK_UN);
} else {
    $checkerr[] = "flock() failed twice. Contact me.";
}

fclose($handle);

//and finally send the data to the data base

if (count($checkerr) == 0) {

    mysql_query("INSERT INTO users (userid, email, name, pass)
    VALUES ('".$genid."', '".$email."', '".$name."', '".$pass."')");

    //<!--begin html--> <- omg html comment

    echo "You have successfully created an account.";

    echo "<br />";
    echo $email;
    echo "<br />";
    echo $name;
    echo "<br />";
    echo $pass;
    
} elseif (count($checkerr) != 0) {
    echo "<ol>";
    foreach($checkerr as $err)
    {
        echo "<li>{$err}</li>";
    }
    echo "</ol>";
    echo "<br />Click <a href=\"http://www.randomns0123.com/contact/\">here</a> if you have an error to report.";
}

mysql_close($con);

?>