警告：遇到非数字值，并且注意：遇到格式不正确的数字值

Question

有人提交用户注册表格时会发生此错误

警告：/public_html/register.php在第55行遇到的非数字值

注意：第55行的/public_html/register.php中遇到的格式不正确的数值

这是第55行的代码

/* If there are no errors continue the registering process */
if(empty($_SESSION['error'])) {
    /* Define some needed variables */ 
    $password   = User::encrypt_password($_POST['username'], $_POST['password']);
    $active     = ($settings->email_confirmation == 0) ? "1" : "0";
    $email_code = md5($_POST['email'] + microtime());
    $date = new DateTime();
    $date = $date->format('Y-m-d H:i:s');

    /* Add the user to the database */
    $stmt = $database->prepare("INSERT INTO `users` (`username`, `password`, `email`, `email_activation_code`, `name`, `active`, `ip`, `date`) VALUES (?, ?, ?, ?, ?, ?, ?, ?)");
    $stmt->bind_param('ssssssss', $_POST['username'], $password, $_POST['email'], $email_code, $_POST['name'], $active, $_SERVER['REMOTE_ADDR'], $date);
    $stmt->execute();
    $stmt->close();

    /* If active = 1 then login the user, else send the user an activation email */
    if($active == "1") {
        $_SESSION['user_id'] = User::login($_POST['username'], $password);
        redirect("status/loggedin");
    } else {
        $_SESSION['success'][] = $language->register->success_message->registration;
        sendmail($_POST['email'], $settings->contact_email, $language->register->email->title, sprintf($language->register->email->content, $settings->url, $_POST['email'], $email_code));
        //printf($language->register->email->content, $settings->url, $_POST['email'], $email_code);
    }
}

编辑

尝试过

$email_code = md5($_POST['email'] . microtime());

并使用点号串联解决了我在评论中发现的问题。