Undefined index

conman101

 <html>
<head>
    <title>Login</title>
   <link href="styles_validate.css" rel="stylesheet" type="text/css">
   </head>
<body>
<?php

session_start();

$postback = $_POST['postback'];

if ($_POST['password'] == 'guest' && strlen($_POST['username']) > 0) //correct inputs
{

	$_SESSION['firstName']=$_POST['username'];
	header("location: index.php");
}
?>
<div class="pageContainer">
<h2>Login</h2><hr>
    <form method="post">
      Please enter your first name:<br>
   <input type="text" name="username" value="<?php echo $name; ?>" size="25"><br>
	  <?php
		if ($_POST['postback'] && (strlen($_POST['username']) < 1 ))//incorrect name
		{
			echo "<font color='red'>Please enter your name.</font>";
			$pagevalid = false;
		}
	  ?>
      <br><br>

  Please enter your password:<br>
  <input type="password" name="password" size="25"><br>
  (Password is "guest")<br>
  <?php
	if ($_POST['password'] != 'guest' && $postback)//incorrect pwd
	{	
	echo "<font color='red'>Please enter the password 'guest'.</font>";
	}
  ?>
  <br><br>
  <input type="submit" value="Login"><br>

  <input type="hidden" name="postback" value="true">
</form>
<a href="index.php">Try going to index.php without logging on.</a>

</div>
</body>
</html>

and I get the errors as follows:

Notice: Undefined index: postback in C:\xampp\htdocs\Site1\login.php on line 12

Notice: Undefined index: password in C:\xampp\htdocs\Site1\login.php on line 14

br />Notice: Undefined variable: name in C:\xampp\htdocs\Site1\login.php on line 25

Notice: Undefined index: postback in C:\xampp\htdocs\Site1\login.php on line 27

Notice: Undefined index: password in C:\xampp\htdocs\Site1\login.php on line 39

bradgrafelman

Welcome to PHPBuilder!

For the undefined index errors, you should never use variables that depend on external data (anything in $POST, $GET or $_COOKIE, etc.) without first verifying that they exist (such as by using [man]isset/man, [man]empty/man, etc.).

As for the undefined variable error, you never attempt to define a variable named $name before using it, so I'm not sure what you were expecting that echo statement to do.