/**
 * 获取Feedburner的用户名
 *
 * @param 
 * @author 编程之家 jb51.cc jb51.cc
 **/
function get_average_readers($Feed_id,$interval = 7){
 $today = date('Y-m-d',strtotime("now"));
 $ago = date('Y-m-d',strtotime("-".$interval." days"));
 $Feed_url="https://Feedburner.google.com/api/awareness/1.0/GetFeedData?uri=".$Feed_id."&dates=".$ago.",".$today;
 $ch = curl_init();
 curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
 curl_setopt($ch,CURLOPT_URL,$Feed_url);
 $data = curl_exec($ch);
 curl_close($ch);
 $xml = new SimpleXMLElement($data);
 $fb = $xml->Feed->entry['circulation'];
 $nb = 0;
 foreach($xml->Feed->children() as $circ){
  $nb += $circ['circulation'];
 }
 return round($nb/$interval);
}


/***   代码来自编程之家 jb51.cc（jb51.cc）   ***/