错误类型：范围（）预期的整数结束参数，得到了LP_c_ulong

Question

I got this error when I try to use 'slots_num' as a parameter in range():

        slots_num = pointer(c_uint32())
        slots = pointer(c_uint32())

        if self.mgetBusSlotsFunc(self.mf, slots_num, slots) != 0:
            raise Exception("Failed to get slots")

        print(devAddr)

        for x in range(0, slots_num):
            print(slots[x])

What I did wrong?

Answer 1

The range built-in function expects integers as its arguments ,

The arguments to the range constructor must be integers (either built-in int or any object that implements the index special method).

but you have provided a pointer instance.

>>> import ctypes
>>> p = ctypes.pointer(ctypes.c_uint32(2))
>>> for i in range(0, p):print(i)
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'LP_c_uint' object cannot be interpreted as an integer

You need to dereference the pointer to get the corresponding value.

>>> d = p.contents.value
>>> d
2
>>> for i in range(0, d):print(i)
... 
0
1