byref(n)返回的相当于C的指针右值&n,本身没有被分配空间:
>>> from ctypes import * >>> n = c_int(0) >>> p = byref(n) >>> pp = byref(p) Traceback (most recent call last): File "<pyshell#4>", line 1, in <module> pp = byref(p) TypeError: byref() argument must be a ctypes instance, not 'CArgObject'
pointer返回的相当于指针左值T* p=&n,可以改变,可以取地址:
>>> from ctypes import * >>> n = c_int(0) >>> q = pointer(n) >>> q.contents = c_int(1) >>> qq = byref(q) >>> dir(qq) ['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_obj'] >>> type(qq) <class 'CArgObject'> #'CArgObject'是什么对象??? >>> qq <cparam 'P' (010AD238)> >>> q <__main__.LP_c_long object at 0x010AD210> >>> q.contents c_long(1)
对于T**参数,通常你得构造一个pointer,然后byref传进去
以__开头并以__结束的属性(class、dir 等)都是为内置方法(built-in method),唯独_obj不是
>>> qq._obj <__main__.LP_c_long object at 0x010B8120> >>> q <__main__.LP_c_long object at 0x010B8120>
由以上执行代码可知,二维指针qq的_obj属性就是该二维指针的首地址,即指向q指针的地址