CODEWITHSUNDEEP
pythonargumentsfunction-pointersctypes
Semih
Semih

Reputation: 33

ctype Linux so library Pointer TypeError

I'm loading a C library (.so file) with ctypes. Then I'm setting arguments and calling one function and got the error below;

ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_ushort instance instead of _ctypes.PyCSimpleType

As I guess it is related to the POINTER definition at the end of 3rd line. Can you help?

import ctypes
mylib = ctypes.cdll.LoadLibrary('./libfocas32.so')
mylib.cnc_allclibhndl3.argtypes = ctypes.c_wchar_p, ctypes.c_ushort, ctypes.c_long, ctypes.POINTER(ctypes.c_ushort)
mylib.cnc_allclibhndl3.restype = ctypes.c_long
h = ctypes.c_ushort
ret = mylib.cnc_allclibhndl3('192.168.1.1',9000,1,(h))

Upvotes: 1

Views: 272

Answers (1)

Michael Butscher
Michael Butscher

Reputation: 10959

(1) h must receive an instance of the type c_ushort, therefore:

h = ctypes.c_ushort()

(2) Assuming that the pointer to h is only used during the function call and shouldn't be stored longer, use

ret = mylib.cnc_allclibhndl3('192.168.1.1',9000,1,ctypes.byref(h))

Upvotes: 1

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