/**     * 外键处理     */    //外部链接增加nofllow $content 内容 $domain 当前网站域名    function content_nofollow($content,$domain){         preg_match_all('/href="(.*?)"/',$content,$matches);         show($matches);         if($matches){         foreach($matches[1] as $val){          if( strpos($val,$domain)===false ) $content=str_replace('href="'.$val.'"', 'href="'.$val.'" rel="external nofollow" ',$content);         }         }         preg_match_all('/src="(.*?)"/',$content,$matches);         if($matches){         foreach($matches[1] as $val){          if( strpos($val,$domain)===false ) $content=str_replace('src="'.$val.'"', 'src="'.$val.'" rel="external nofollow" ',$content);         }         }         return $content;    }