如題，我要做帳號密碼註冊的頁面，需檢查兩次帳號密碼是否輸入一致，若不一致出現錯誤提示於輸入格後方，不知道為什麼我按下註冊後上面的HTML都還在但就是不會刷新$errus的值並顯示在頁面上，我問chatpgt也沒有答案求大大幫忙!!感激不盡><
p.s. vardump($errus)有顯示"帳號輸入不一致"，但帳號輸入格後方是原本的空白
以下為程式碼

<?php
session_start();
print "hello";
$username='';
$password='';
$username2='';
$password2='';
$errus='';
$errpa='';
$html=<<<EOT
    <form action='login0.php' method='post'>
    <p>請輸入帳號(username)：
    <input type='text' name='username' required value=$username>
    <p>請再次輸入帳號(username)：
    <input type='text' name='username2' required value=$username2> $errus
    <br><br>
    <p>請輸入密碼(password)：
    <input type='password' name='password' required value=$password>
    <p>請再次輸入密碼(password)：
    <input type='password' name='password2' required value=$password2> $errpa
    <input type='submit' name='register' value=註冊>
    
    </form>
EOT;
print $html;

mysqli_report(MYSQLI_REPORT_OFF);
if(isset($_POST['register'])&&$link=@mysqli_connect('localhost','root','','users'))
{
    
    if(!empty($_POST['username'])&&!empty($_POST['username2'])&&!empty($_POST['password'])&&!empty($_POST['password2']))
    {
        $username=$_POST['username'];
        $username2=$_POST['username2'];
        $password=$_POST['password'];
        $password2=$_POST['password2'];
        $correct=1;
        
        if($_POST['username']!==$_POST['username2'])
        {
            $errus="<p><font color=red>帳號輸入不一致，請重新輸入!";
            echo $errus;
            //var_dump($errus);
            $correct=0;
            //echo "n";
        }
        if($_POST['password']!==$_POST['password2'])
        {
            $errpa="<p><font color=red>密碼輸入不一致，請重新輸入!";
            echo $errpa;
            $correct=0;
        }
        if($correct)
        {
            echo "a";
            $sql="SELECT username FROM customers WHERE username=?";
            $stmt = mysqli_prepare($link, $sql);
            mysqli_stmt_bind_param($stmt, "s", $username);
            mysqli_stmt_execute($stmt);
            //$result = mysqli_stmt_get_result($stmt);
            //var_dump($result);
            mysqli_stmt_store_result($stmt);  //將結果保存在 stmt 對象中
            $num_rows = mysqli_stmt_num_rows($stmt);  //獲取記錄數
            if($num_rows>0)
            {    $errus="<font color='red'>帳號已被使用，請重新輸入!";               
            }
            else
            {
                
                $sql = "INSERT INTO customers (username, password) VALUES (?, ?)";
                $stmt = mysqli_prepare($link, $sql);
                mysqli_stmt_bind_param($stmt, "ss", $username, $password);
                if (mysqli_stmt_execute($stmt) === TRUE) {
                    //註冊成功後重定向到登錄頁面
                    header("Location: login.php?success=1");
                    //當被重定向到 login1.php 時，URL 中的 ?success=1 會觸發顯示成功訊息。
                    exit();
                }
            }
        }
        
    }

}else print mysqli_connect_error();
?>