Share cookie between subdomain and domain

Question

I have two questions. I understand that if I specify the domain as .mydomain.com (with the leading dot) in the cookie that all subdomains can share a cookie.

Answer 1

Simple solution

setcookie("NAME", "VALUE", time()+3600, '/', EXAMPLE.COM);

Setcookie's 5th parameter determines the (sub)domains that the cookie is available to. Setting it to (EXAMPLE.COM) makes it available to any subdomain (eg: SUBDOMAIN.EXAMPLE.COM )

Reference: http://php.net/manual/en/function.setcookie.php