[新手发帖]字符串拼接 & 出现的问题

              $postData = array(
'amount'=>10,
'jspay_flag'=>4,
'merchant_id'=>$config['merchantId'],
'nonce_str'=>123,
'notify_url'=>'htts://www.baidu.com',
'pay_way'=>'WXZF',
'service'=>'get_tdcode',
'third_order_id'=>"DJ20180606095731449",
);
$str = "";
foreach($postData as $key=>$val){
$str.= '&'.$key.'='.$val;
}

             &amount=10&jspay_flag=4&merchant_id=0000000018&nonce_str=123¬ify_url=htts://www.baidu.com&pay_way=WXZF&service=get_tdcode&third_order_id=DJ20180606095731449

notify_url 乱码？？？？？？？？？