Cannot Modify Header Information

[pureDesi]

Ok, I have a problem that I'm guessing has a very simple fix. But I can't seem to find it.
This is the exact contents of the file:
[code]<?
setcookie("test", "", time()-30);
setcookie("test", $_GET['value'], time()+30);
echo $HTTP_COOKIE_VARS["test"];
?>[/code]

When I run it the first time, it's fine, but then everytime after that I get the following error message:
[code]Warning: Cannot modify header information - headers already sent by (output started at /home2/monkey/public_html/main/test.php:3) in /home2/monkey/public_html/main/test.php on line 3[/code]
Anybody know what's wrong?

[schwim]

Hi there,

Are you sending any POST data along with the script when the next page loads?  I got this same error when I was trying to use a user authorization script, and the explanation I found was that once headers are sent and page data starts to get passed, you can't go back and add any more header information.

One of the solutions I found was ob_start and ob_end_flush, but I have yet to make this work successfully.

thanks,
json

[akitchin]

i'm locking this topic.  read the sticky topics, as they discuss header errors in detail.