php - How to write session for both www. and non-www version of my domain?

Question

I'm writing session on mydomain.com/login.php I believe this can't be accessed in www.mydomain.com. Is that right?

How can I write to $_SESSION so I can access it from both the www. and non-www version of my domain?

Answer 1

have a look at session_set_cookie_params it explains setting . in the domain will allows for access to subdomains as well,

Cookie domain, for example 'www.php.net'. To make cookies visible on all 
subdomains then the domain must be prefixed with a dot like '.php.net'.

miki has an example

http://www.php.net/manual/en/function.session-set-cookie-params.php#94961