function setCookie(c_name,value,expiredays){
	var exdate=new Date();
	exdate.setDate(exdate.getDate()+expiredays);
	document.cookie=c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toUTCString());
};

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 "";
};

function checkCookie(){
username=getCookie('username');
if (username!=null && username!=""){
  alert('Welcome again '+username+'!');
  }else{
  username=prompt('Please enter your name:',"");
  if (username!=null && username!=""){
    setCookie('username',username,365);
    }
  }
};

function eraseCookie(name) { 
    setCookie(name,"",-1); 
}

function leeCookie(nombre) {
	var cookies=document.cookie; if(!cookies) return false;
	var comienzo=cookies.indexOf(nombre);
	if(comienzo==-1) return false;
	comienzo=comienzo+nombre.length+1;
	cantidad=cookies.indexOf("; ", comienzo)-comienzo; if(cantidad<=0) cantidad=cookies.length;
	return cookies.substr(comienzo, cantidad);
};