ctypes - Passing an array from python to shared DLL, seeing access violation error -

the c function dll:

multi(double freq, double power, int ports[], int size) need pass 3rd parameter array python  

tried following different codes:

a:

import ctypes pyarr = [2,3] arr = (ctypes.c_int * len(pyarr))(*pyarr)  lp = cdll(cdll_file) lp.multi(c_double(freq), c_double(power), arr ,c_int(size))` 

this code shows error ## exception :: access violation reading 0x00000000000

b:

retarr = (ctypes.c_int*2)() retarr[0] =2 retarr[1] =3  lp = cdll(cdll_file) lp.multi(c_double(freq), c_double(power), retarr ,c_int(size))` 

this code shows error

## exception :: access violation reading 0x00000000000  

c: same code using ctypes.byref tried ......

my understanding function expects array argument , tries passing array such address. both cases , didn't work sees mistake in understanding or other work out ??

specify argtypes. given test.dll source:

#include <stdio.h>  __declspec(dllexport) void multi(double freq, double power, int ports[], int size) {     int i;     printf("%f %f\n",freq,power);     for(i = 0; < size; ++i)         printf("%d\n",ports[i]); } 

this works:

from ctypes import * dll = cdll('test') multi = dll.multi multi.argtypes = (c_double,c_double,pointer(c_int),c_int) multi.restype = none  ports = (c_int * 2)(100,200) multi(1.1,2.2,ports,len(ports)) 

output:

1.100000 2.200000 100 200