function create_cookie(name,value,expirydate)
{
    var date = new Date();
    date.setDate(date.getDate()+expirydate);
    document.cookie = name+"="+escape(value)+((expirydate==null) ? "" : "; expires="+date.toGMTString())+"; path=/";

}
function read_cookie(cookie_name)
{

       if(document.cookie.length > 0)
       {
              cookie_start = document.cookie.indexOf(cookie_name+"=");
                 if(cookie_start != -1)
                         {
                            cookie_start = cookie_start+cookie_name.length+1;
                            cookie_end = document.cookie.indexOf(";",cookie_start);
                            if(cookie_end == -1) cookie_end = document.cookie.length;
                            return unescape(document.cookie.substring(cookie_start,cookie_end));
                         }
        }
    return "";
}