Header Warning

[waverider303]

I get this warning when I am trying to refresh the page to a different one:

 

Warning: Cannot modify header information - headers already sent by (output started at /home/ada/public_html/v2/ada_login/main.php:9) in /home/ada/public_html/v2/ada_login/main.php on line 36

 

Here is the code:

<?php
if($session->logged_in){
header("Refresh: 3 url=welcome.php?uid=$session->userid");
        echo '<h3>Creating workspace</h3>';
echo '<img src="images/loader.gif" />';
}
?>

[rajivgonsalves]

read this topic it explains why

 

http://www.phpfreaks.com/forums/index.php/topic,37442.0.html

[waverider303]

The weird thing is that this works on another site of mine. It only fails on another site I am trying to incorporate this script into. Is related to a specific version of PHP?

[rajivgonsalves]

why it worked on one site and not another the output buffering must be on on the site it worked

[waverider303]

Is this something that should be on or off? Is there any effect when the buffer output is on?

[rajivgonsalves]

I am not sure but I think I read somewhere it increases performance of your page. maybe someone else in the forum could shed some light on this 

[premiso]

It is generally better to code for output buffer off, especially if you plan on selling or giving the script away. But it also depends on what you are doing, for instance, if you plan on gzipping your pages up, it would be better to have output buffer on so you can serve that out easier.

 

But for most scripts you should have it off and do proper coding where you store output in a variable and echo it out at the end of the script, so you do not mix processing with outputting, to avoid errors such as this no matter the circumstance. That and output buffering is considered a "bandaid" for solving header errors.