分析错误：语法错误，意外'$用户名'；（T#u变量），应为'；]'；在第15行的/home/xxx/public_html/dashboard.php中

我在运行php代码时遇到以下错误。我正在尝试创建注册表，但它始终显示以下错误消息

分析错误：语法错误，第15行的/home/xxx/public\u html/dashboard.php中出现意外的“$username”（T_变量），应为“]”

请帮我解决这个问题

<?php
  session_start();
  require 'config.php'; 
  if (isset($_POST['register_btn])){
     session_start();
     $username = mysql_real_escape_string($_POST["username"]);
     $firstName = mysql_real_escape_string($_POST["firstName"]);
     $lastName = mysql_real_escape_string($_POST["lastName"]);
     $email = mysql_real_escape_string($_POST["email"]);
     $password = mysql_real_escape_string($_POST["password"]);
     $password2 = mysql_real_escape_string($_POST["password2"]);
     if ($password == $password2){
        $password = md5($password);
       $sql = "INSERT INTO users(username, firstName, lastName, email, password, password2) 
       VALUES('$username', '$firstName', '$lastName', '$email', '$password', '$password2')"; 
       mysqli_query($conn, $sql);
       $_SESSION['message'] = "You are successfully logged in";
       $_SESSION['firstName'] = $firstName;
       $_SESSION['lastName'] = $lastName;
   }else {
        $_SESSION['message'] = "The Two password do not match";
       }

    }


?>

---

如果（isset（$\u POST['register\u btn']）{

，您忘了关闭

中的单引号
'

运行下面的代码

<?php
  session_start();
  require 'config.php'; 
  if (isset($_POST['register_btn'])){
     session_start();
     $username = mysql_real_escape_string($_POST["username"]);
     $firstName = mysql_real_escape_string($_POST["firstName"]);
     $lastName = mysql_real_escape_string($_POST["lastName"]);
     $email = mysql_real_escape_string($_POST["email"]);
     $password = mysql_real_escape_string($_POST["password"]);
     $password2 = mysql_real_escape_string($_POST["password2"]);

    if ($password == $password2){

       $password = md5($password);
       $sql = "INSERT INTO users(username, firstName, lastName, email, password, password2) 
       VALUES('$username', '$firstName', '$lastName', '$email', '$password', '$password2')"; 
       mysqli_query($conn, $sql);
       $_SESSION['message'] = "You are successfully logged in";
       $_SESSION['firstName'] = $firstName;
       $_SESSION['lastName'] = $lastName;

    }else {
        $_SESSION['message'] = "The Two password do not match";
    }

  }

?> 

你甚至可以在这里发现语法错误，因此查看语法突出显示。你不能自己？
$\u POST['register\u btn]
是你的问题。@Scuzzy-谢谢你解决了这个问题。你能推荐任何免费的工具来纠正php中的简单错误吗？我是初学者，所以对这些工具没有太多的知识。@PrashantGorule一个好的php IDE应该马上给你反馈你的代码。虽然我不免费使用，但请不要鼓励输入错误通过回答他们，他们应该被关闭。