Código PHP:
setcookie("TestCookie","Test Value");
setcookie("TestCookie",$value,time()+3600); /* expire in 1 hour */
setcookie("TestCookie",$value,time()+3600,"/~rasmus/",".utoronto.ca",1);
http://es2.php.net/manual/es/function.setcookie.php Código PHP:
setcookie("username", "$username", time()+315360000, "/", "www.mydomain.com");
instead of just
setcookie("username", "$username", time()+315360000, "/", "mydomain.com");
or even just
setcookie("username", "$username", time()+315360000);