Hey i need help with this, anyone good with php should let me know:
I'm trying to use the header() function to pull a certain variable from the previous page to use in the next one. here's the code
if (!$_GET[topic_id] ){ header(location: prevpage.php);
exit;
}
instead i'm gettin 'cannot modify headers, header already sent' error. i've used it b4, so i'm stomped. any ideas?

1. Make sure there is no space at the top of the page
2. make sure u have not outputed any data before using the function

<?php
if (!$_GET['topic_id'] ){

header("location: prevpage.php";
exit;
}

?>

Onydic you missed the quote "." ("location: prevpage.php";

well, i used the quotes in the original. and the thing is, when i put it at the top of the page, it justs loads the previous page back! i'm stomped cos, i've used it before, and it worked.

Can you post your code let's have a look at it?

If you've already echoed any content at the top of your file, then you can't use the header() function except you're using output buffering [let's not talk about that].

If you have outputted any content, before calling header(), you'll receive a warning. All header() calls are to be made before outputting any content, which is why I'm asking to see your code. Perhaps I could help you rewrite it.

onydchic, they are right. It's one of the first problems people encounter when learning PHP.

You cannot use the Header() Function after sending any output. There must be no space before your <?php segment and no echo statement before the Header() statement. Make sure you check all include()ed php files too.

well, thanks all! i've solved the problem! turns out i forgot to generate the link from the previous page using the 'topic.id' variable!

Anytime baby, more o r o r o 2 ur elbow,