I'm new to php and I'm following a tutorial to make a login panel. It works fine on the demo website but when I download the code and run on my machine, 5 notices popped up. They all look like: "Notice: Undefined index: submit in C:\xampp\htdocs\myfolder\demo.php on line 24".
From other programming experiences I think that these means I didn't define the variables before using them. However, these variables seem to be existing in the system (from what I understand reading other questions >-<).
I attached my code below and marked the undefined index on the right. Can anyone help me explain what's wrong with the code and how can I solve it? Thanks a lot!
<?php
session_name('Login');
session_start();
if($_POST['submit']=='Login') //undefined submit
{
$err = array();
if(!$_POST['username'] || !$_POST['password'])
$err[] = 'All the fields must be filled in!';
if(!count($err))
{
$_POST['username'] = mysql_real_escape_string($_POST['username']);
$_POST['password'] = mysql_real_escape_string($_POST['password']);
// Escaping all input data
$row = mysql_fetch_assoc(mysql_query("SELECT id,user FROM writers WHERE user='{$_POST['username']}' AND pass='".md5($_POST['password'])."'"));
if($row['user'])
{
$_SESSION['user']=$row['user'];
$_SESSION['id'] = $row['id'];
// Store some data in the session
}
else $err[]='Wrong username and/or password!';
}
if($err)
$_SESSION['msg']['login-err'] = implode('<br />',$err);
// Save the error messages in the session
header("Location: demo.php");
exit;
}
$script = '';
if($_SESSION['msg'])
{
// The script below shows the sliding panel on page load
...
}
?>
<head>
......
</head>
<body>
<!-- Panel -->
<div id="toppanel">
<div id="panel">
<div class="content clearfix">
<?php
if(!$_SESSION['id']): //undefined id
?>
<div class="left">
<form class="clearfix" action="" method="post">
<h1>Writer Login</h1>
<?php
if($_SESSION['msg']['login-err']) //undefined login-err
{
echo '<div class="err">'.$_SESSION['msg']['login-err'].'</div>';
unset($_SESSION['msg']['login-err']);
}
?>
//Login form
</form>
</div>
<?php
endif;
?>
</div>
</div> <!-- /login -->
<!-- The tab on top -->
<div class="tab">
<ul class="login">
<li class="left"> </li>
<li>Hello <?php echo $_SESSION['user'] ? $_SESSION['user'] : 'Guest';?>!</li> //undefined user
<li class="sep">|</li>
<li id="toggle">
<a id="open" class="open" href="#"><?php echo $_SESSION['id']?'Open Panel':'Log In';?></a> //undefined id
<a id="close" style="display: none;" class="close" href="#">Close Panel</a>
</li>
<li class="right"> </li>
</ul>
</div> <!-- / top -->
</div> <!--panel -->
Sorry for the long code! I really not sure which ones will be relevant to the problem and do not dare to delete more. Thank you for your patience!
You need to check if that variable exists before you use it. You would use
isset()for that:If you're just checking to see if the form was submitted you could just check to see if the page was request via
POSTinstead: