header function problem

this is the login check i included at the top of my page.


<?

session_start();

if(!session_is_registered('username')){

header( "Location: http://localhost/login.htm" );

}else{


}
?>

I still had this showing at the top of my page though
Warning: Cannot send session cache limiter - headers already sent (output started at /usr/local/httpd/htdocs/start/home.php:2) in
/usr/local/httpd/htdocs/start/home.php on line 6


the exit only works when i put it after the code for login.html

I guess a session cookie is sent when you check to see if the variable is registered. Try using ob_start() at the top and ob_flush() (or another of the ob_ functions) at the end to consolidate headers.

First thing is that you always want to exit the script after a header call, so your code should look like:

However, you should try registering your session variables like this:

Now you can find out if that session variable exists with this code

I agree with Laidbak on the $_SESSIONS issue... You should definitely make use of the superglobals... Newer versions of PHP have "register_globals" turned off, and so using the superglobal arrays ($_POST, $_GET, $_SERVER, $_SESSIONS, etc.) will ensure that you application will be portable among many different versions.



You'll want to also make sure that the opening "<?php" is on the FIRST line of your file. If there is any whitespace (blank lines, etc.), you will also receive this error message.

HTH!

For reference, you can also encapsulate the header() function within the exit() function: