/** 
* Sets a Cookie with the given name and value. 
* From [url]http://www.linglihu.com/[/url]
* name Name of the cookie 
* value Value of the cookie 
* [expires] Expiration date of the cookie (default: end of current session) 
* [path] Path where the cookie is valid (default: path of calling document)  

* [domain] Domain where the cookie is valid 
* (default: domain of calling document) 
* [secure] Boolean value indicating if the cookie transmission requires a 
* secure transmission 
*/

function setCookie(name, value, expires, path, domain, secure)
{ 
  document.cookie = name + "=" + escape(value) + 
                    ((expires) ? "; expires=" + expires.toGMTString() : "") + 
                    ((path) ? "; path=" + path : "") + 
                    ((domain) ? "; domain=" + domain : "") +  
                    ((secure) ? "; secure" : ""); 
}

/** 
* Gets the value of the specified cookie. 
*  From [url]http://www.linglihu.com/[/url]
* name Name of the desired cookie. 
* 
* Returns a string containing value of specified cookie, 
* or null if cookie does not exist. 
*/
function getCookie(name)
{ 
  var dc = document.cookie;  
  var prefix = name + "="; 
  var begin = dc.indexOf("; " + prefix); 

  if(begin == -1) { 
    begin = dc.indexOf(prefix); 
    if(begin !== 0) {return null;}  
  }
  else { 
    begin += 2; 
  }
  
  var end = document.cookie.indexOf(";", begin); 
  if (end == -1) {
    end = dc.length; 
  }
  
  return unescape(dc.substring(begin + prefix.length, end)); 
}

/** 
* Deletes the specified cookie. 
* From [url]http://www.linglihu.com/[/url] 
* name name of the cookie 
* [path] path of the cookie (must be same as path used to create cookie) 
* [domain] domain of the cookie (must be same as domain used to create cookie) 
*/ 
function deleteCookie(name, path, domain)
{ 
  if(getCookie(name)) {
    document.cookie = name + "=" + 
                      ((path) ? "; path=" + path : "") + 
                      ((domain) ? "; domain=" + domain : "") + 
                      "; expires=Thu, 01-Jan-70 00:00:01 GMT"; 
  }
}