function getCookie(c_name)
{
if (document.cookie.length>0)
{ 
c_start=document.cookie.indexOf(c_name + "=")
if (c_start!=-1)
{ 
c_start=c_start + c_name.length+1 
c_end=document.cookie.indexOf(";",c_start)
if (c_end==-1) c_end=document.cookie.length
return unescape(document.cookie.substring(c_start,c_end))
} 
}
return null
} 

function setCookie(c_name,value,expiredays)
{
	var exdate=new Date()
		exdate.setTime(exdate.getTime()+(expiredays*24*3600*1000));
document.cookie=c_name+ "=" +escape(value)+
((expiredays==null) ? "" : "; expires="+exdate);
}
	
function checkCookie(username)
{
username=getCookie(username)
if (username!=null)
  {alert('<< '+username+' >>!')}
else 
  {username=prompt('Please enter your name:',"")
  setCookie('username',username,365)}
}