php json_encde 转换空对象和空数组 为json格式

1.加了JSON_FORCE_OBJECT参数的json_encode($foo,JSON_FORCE_OBJECT)得到的是

{
  "bar1": {},
  "bar2": {}
}

2.(object)

$foo = array(
  "bar1" => (object)array(), // Should be encoded as an object
  "bar2" => array() // Should be encoded as an array
);

echo json_encode($foo);
// {"bar1":{}, "bar2":[]}