To understand PHP's header() - php

Question

Where do you use the command header()?
I have the following code at handlers/handle_login.php. The user has gone to the site from index.php which is the starting place.
if(!$logged_in){
header("Location: index.php");
die("You are not logged_in");
}
If if-clause is true, I get a 404 error, since the header puts me to to handlers/index.php, instead of index.php.

Answer 1

While I agree with nilamo and earl, I hope I can give a bigger picture:
Using relative paths can have very strange effects depending on where the browser
'thinks' it is in your site hierarchy. For example, assume the site has an index file '/index.php' but is configured to accept module and action in the URI path. You may very well have a url that looks like:
http://www.yoursite.com/forms/contact/
From this situation, returning a header like:
header("Location: index.php");
may very well cause the browser to try to request
http://www.yoursite.com/forms/contact/index.php
which is obviously not what you want. For this reason, it's generally better to use '/index.php' as recommended above, or even better use the fully qualified URL when possible.
Hope this helps.

Answer 2

Set the location to the complete URL of the index.php, not just the filename. According to php.net, this is the right way to do it, don't use relative paths. Here is an example:
if(!$logged_in){
header("Location: http://exampledomain.com/index.php");
die("You are not logged_in");
}

Answer 3

Try using '/':
if(!$logged_in){
header("Location: /index.php");
die("You are not logged_in");
}
Without a slash, it is assumed that you're referring to something in the current directory. By sticking that slash at the front, you're explicitly referring to the file at the root of the site. Since the page is 'index.php', you could just as easily use "header('Location: /')".