This function redirects the client. This is done by issuing a Location: header and exiting.
Example 48-1. Redirecting to another site
Example 48-2. Local redirect
This function can be called statically.
Avoid sending any kind of data to the client before calling redirect().
The location header requires an absolute URL. If not given, redirect() tries to build one from $url. So if the redirect fails, set the absolute URL manually as argument.