每当我在我的 html 上使用 if else 时，我都会不断收到错误 [关闭]

Question

我们被要求创建一个网站，我想问一下我的表单是否有问题，因为每当我在浏览器上打开它时，我的 html 结束标记总是出错。

---

<?php 
 session_start();
 include('connect.php');
 ?>

<?php

  if (isset($_POST['Login'])){

$username=$_POST['username'];
$password=$_POST['password'];

$login_query=mysql_query("select * from user where username='$username' and     password='$password' and Usertype='admin'") or die(mysql_error());
$login_query1=mysql_query("select * from user where username='$username' and password='$password' and Usertype='user'") or die(mysql_error());



$count=mysql_num_rows($login_query);
$count1=mysql_num_rows($login_query1);

$row=mysql_fetch_array($login_query);
$row1=mysql_fetch_array($login_query1);

?>
<!DOCTYPE html>
<head>
<link rel="stylesheet" type="text/css" href="mystylelogin.css"> 
</head>
<body style="background-color: #66A9EB">
    <header>
        <div class="header"><h1><a href="login.php">Tidbits<a></h1></div>
        <div class="header-cont"> 
    </header>
<form method="POST" action="home.php">
        <fieldset>
                <p> Welcome </p>
                    <br>
                    Username: <input type="text" name="uname">
                    <br><br><br>
                    Password: <input type="password" name="pword">
                    <br>
                <div id="button">
                    <br>
                    <input type="submit" style="font-family: Verdana; color: white; font-size: 20px; background-color: #99CCFF; border: 1px solid #3399FF; border-radius:5px; margin-left: 150px" name="do" value="Log In"/>    
                </div>
                <div>
                    <P>

                </div>
            <p id="create"><a href="register.php">Create an Account</a></p>
 <?php 
                        if($count == 1){
                        $_SESSION['id']=$id;
                        header('Location:  admin.php');

                        }
                        if($count1 == 1){
                        session_start();
                        $_SESSION['id']=$id;
                        header('location:user.php');
                        }

                ?>


        </fieldset>
    </form>
<!----------------------------------SLIDESHOW------------------------------------------------------->
    <script type="text/javascript">

        var slideimages = new Array() // create new array to preload images
        slideimages[0] = new Image() // create new instance of image object
        slideimages[0].src = "cookiesandcream.jpg" // set image src property to image path, preloading image in the process
        slideimages[1] = new Image()
        slideimages[1].src = "pizza.jpg"
        slideimages[2] = new Image()
        slideimages[2].src = "waffle.jpg"

        </script>
        </head>
        <body>
        <img src="cookiesandcream.jpg" id="slide" width="700" height="500" />

        <script type="text/javascript">

        //variable that will increment through the images
        var step=0

        function slideit(){
         //if browser does not support the image object, exit.
         if (!document.images)
          return
         document.getElementById('slide').src = slideimages[step].src
         if (step<2)
          step++
         else
          step=0
         //call function "slideit()" every 2.5 seconds
         setTimeout("slideit()",2500)
        }

        slideit()
    </script>

    </body>
    </html>

您能告诉我代码中的错误吗？

Answer 1

header 必须在任何输出完成之前位于页面顶部（在您开始 html 之前）

将其移至 doctype 标签上方：

if($count == 1){
    $_SESSION['id']=$id;
    header('Location:  admin.php');
}

if($count1 == 1){
    // session_start(); ---------- remove this line as you already started the session at the top of the page
    $_SESSION['id']=$id;
    header('location:user.php');
}

more information about header

你错过了打开html标签：

<!DOCTYPE html>
<html>

而且您还没有关闭最初的 if (isset($_POST['Login'])){ - 您需要关闭 }

您还需要在初始幻灯片脚本之后删除以下标签：

</head>
<body>

Answer 2

您的意思是您收到一条消息说您的 html 无效？缺少您的起始 <html> 标记。 正确的标记如下所示：

<!DOCTYPE html>
<html>
<head>
    <title>Some Website</title>
</head>
<body>
    …
</body>
</html>

Answer 3

您缺少第一个 if 语句末尾的右大括号。

适当的缩进将极大地帮助您在未来发现这些错误，如果您遇到问题无法发现，请尝试通过 php 验证器运行代码，例如 http://phpcodechecker.com/