Small PHP issue: Undefined Index

Alex · Dec 30, 2011

I'm getting an undefined index on lines 15-19. The code works fine and I can disable the error messages, but I'm wondering why.

PHP:

<?php
session_start();

if (($_SESSION)==NULL){
 echo "Welcome, guest";
 echo "   <a href='login.php'>Login</a>";
 $postedby = "Guest";
}
else{
	echo "Welcome, " . $_SESSION['username'];
	echo "   <a href='logout.php'>Logout</a>";
	$postedby = $_SESSION['username'];
}

$submit = $_POST['submit'];
$heading=$_POST['heading'];
$details = $_POST['details'];
$section = $_POST['section'];
$location = $_POST['location'];
$contactinfo = $_POST['contactinfo'];
$date = date("Y-m-d");


if ($submit){
	if ($heading&&$details&&$section){
		include"config.php";
		$sql = "INSERT into posts (heading, details, location, section, date, postedby, contactinfo)"
				."values ('$heading', '$details', '$location', '$section', '$date', '$postedby', '$contactinfo')";	
		$result = mysql_query($sql);
		if($result){
			header('Location: successpost.php');		
		}
		else{
			echo "Please fill out all the fields";
		}
}
}
?>
<html>
<head>
<title>LessonWorld</title>

</head>

<body>
<form action="post.php" method="POST">
	<table>
		<tr>	
			<td>
			Ad title:
			</td>
			<td>
			<input type='text' name='heading'>
			</td>
		</tr>
		<tr>	
			<td>
			Ad content:
			</td>
			<td>

			<script language="javascript" type="text/javascript">
	function limitText(limitField, limitCount, limitNum) {
		if (limitField.value.length > limitNum) {
			limitField.value = limitField.value.substring(0, limitNum);
		} else {
			limitCount.value = limitNum - limitField.value.length;
		}
	}
	</script>
	<textarea name="details" rows="6" cols="60" onKeyDown="limitText(this.form.details,this.form.countdown,1000);" 
	onKeyUp="limitText(this.form.details,this.form.countdown,100 rows="10" cols="60");">
	</textarea><br>
	<font size="1">(Maximum characters: 1000)<br>
	You have <input readonly type="text" name="countdown" size="3" value="1000"> characters left.</font>
	</form>
			</td>
		</tr>
		<tr>	
			<td>
			Location:
			</td>
			<td>
			<input type='text' name='location'>
			</td>
		</tr>
		<tr>	
			<td>
			Specify how you wish to be contacted:
			</td>
			<td>
			<input type='text' name='contactinfo'>
			</td>
		</tr>
		<tr>	
			<td>
			Select section:
			</td>
			<td>
			<select name="section">
			<option value="Hockey Lessons" selected="selected">Hockey Lessons</option> 
			<option value="Football Lessons" selected="selected">Football Lessons</option> 
			<option value="Ping-pong Lessons" selected="selected">Ping-pong Lessons</option> 
			</td>
		</tr>
	</table>
	<input type='submit' name='submit' value='Post ad'>
</form>
</body>
</form>
</html>

Same issue here on lines 16-17

PHP:

<!DOCTYPE html>
<html>
<head>
<title>LessonWorld</title>
</head>

<body>

<p>Do you agree with the following <a href="terms.html">terms</a>?</p>
<form action="agreement.php" method="POST">
<input type="checkbox" name="agree" value="accept" /> Yes<br />
<input type="submit" name='submit' value="continue" >
</form>
</html>
<?php
$agree = ($_POST['agree']);
$submit = $_POST['submit'];

if ($submit){
	if( isset($_POST['agree']) )
	{
		header('Location: post.php');
	}
	else if (! isset($_POST['agree']) )
	{
		echo "You must accept to continue.";
	}

}
	
?>

Thank you!

DesignerBill · Dec 31, 2011

Just be sure your code is trying to process the $_POST variables after submitting the form, not before. Also, you can't change the header location:

Code:

 header('Location: successpost.php');

after sending any output to the browser with HTML code or with PHP echo.

For future PHP issues, you might want to post them in the "Programming" forum.

conor · Jan 1, 2012

also another usefull trick is phps built in error suppressor - the at (@) symbol. See http://www.php.net/manual/en/language.operators.errorcontrol.php.

You can put this symbol before variables or functions to suppress any errors that should be created. I usually use it for form validation as it doesn't really matter if the variable is set, just that it has a value. Here's a quick example:

Code:

$submit = @$_POST[ 'submit' ];

Small PHP issue: Undefined Index

Alex

New Member

DesignerBill

Member

conor

New Member