通过一个变量返回几个错误

对于我的注册表单，我有一个函数可以检查所有字段是否正确。

如果字段不正确，则通过与$_SESSION['errors'] = $errors;的会话传递变量$errors，并将用户发送回显示错误消息的注册页面。

我想做的是能够在每个错误输入旁边显示一条错误消息，因此，例如，如果一个用户没有同时输入他的用户名/密码，并且captcha错误，就会显示这样的内容：

[输入用户名]请输入您的用户名

[输入密码]需要密码

[电子邮件输入]

[验证码输入]重试

我知道我可以通过为每个错误设置一个不同的变量来创建它，并将它们全部传递到会话中，然后检查它们是否都设置好了，但这看起来不太干净。

我该如何做到这一点？使用$errors作为数组，这样我就可以为每个不正确的输入存储一个错误？（我还没有学会使用它们，但如果是这样的话，我会的）。

这是我的代码，更清晰：

            if (!isset($username) || $username == ''){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (!ctype_alnum($username)){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (gg::getUser($username)){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (gg::getUser($email, 'email')){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (!isset($password) || $password == ''){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (!isset($passwordconf)){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (!isset($_POST['captcha'])){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if ($password != $passwordconf){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if (filter_var($email, FILTER_VALIDATE_EMAIL) == false){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }
            if ((int)$captcha != (int)$_SESSION['captcha_answer']){
                    $errors = "";
                    gg::writeLog('registration failed - error');
                }

if ($error != false) {
            $_SESSION['errors'] = $errors;
            header('Location: ' .ggconf::get('base_url'). '/user/register.php');
        }

$errors = //array
if (!isset($username) || $username == ''){
        $errors['username']= "username error";
        gg::writeLog('registration failed - error');
    }
  if (gg::getUser($email, 'email')){
        $errors['email']= "email error";
        gg::writeLog('registration failed - error');
    }
    ......

<?php 
if(isset($errors['username'])){
  echo $errors['username'];
}?>
//html for username input 
$errors= array(
    "username" => "bar",
    "email" => "foo",
);