Python 3.7 - Passing parameters to DLL using ctypes

Question

I have the following code:

num1=10.1234
int1=10
ret=GetOutput(int1,num1)

The function GetOutput is defined as

def GetOutput(int2, num2):
  lib = ctypes.WinDLL("mydllname.dll")
  prototype = ctypes.WINFUNCTYPE(ctypes.c_int, ctypes.c_int, ctypes.POINTER(ctypes.c_double * 4096))
  paramflags = (1, "int2",), (1, "num2",),
  GetOutput = prototype(("GetOutput", lib), paramflags)    
  ret=GetOutput(int2, num2)
  return ret

i get the following error and I am requesting your kind help.

LP_c_double_Array_4096 instance instead of float

If I convert num1 as:

num1=list(range(4096))
int1=10
ret=GetOutput(int1,num1)

I get the following error:

LP_c_double_Array_4096 instance instead of list

if I convert the num1 into array as follows:

num1=list(range(4096))
int1=10        
for item in num1:
    arrayA = array("i", num1)
ret=GetOutput(int1,arrayA)

i get the following errors:

<class 'TypeError'>: expected LP_c_double_Array_4096 instance instead of array.array

Please explain as much as possible as I am new to programming and only have very preliminary/basic understanding of OOPS, lists, tuples, pointers etc and no clue about ctypes.

Thanks

Answer 1

Thanks all, the following code is working - I have made a mistake in understanding what the dll is doing.

num2 is not an input but an output and hence the paramflags would change. Doing this allows any arbitrary declaration of num1.Since paramflags changed, calling the function Getoutput_Sub requires only one input now. Previously, I got confused by using the same function name.

num1=10.1234
int1=10
ret=GetOutput_Main(int1,num1)

The above is where the function is being called and the below is how the function is defined

def GetOutput_Main(int2, num2):
    lib = ctypes.WinDLL("mydllname.dll")
    prototype=ctypes.WINFUNCTYPE(ctypes.c_int,ctypes.c_int,ctypes.POINTER(ctypes.c_double * 4096))
    paramflags = (1, "int2",), (2, "num2",),
    GetOutput_Sub = prototype(("GetOutput", lib),paramflags)    
    ret=GetOutput_Sub(int2)
    return ret

In my comment earlier, I said two functions and a structure. It is actually three functions; two that I am writing and one function (passing a string in quotes) that is standard for the dll.