How do I wrap this C function, with multiple arguments, with ctypes?

Question

Hi everyone! I have the function prototype here:

extern "C" void __stdcall__declspec(dllexport) ReturnPulse(double*,double*,double*,double*,double*);

I need to write some python to access this function that is in a DLL. I have loaded the DLL, but each of the double* is actually pointing to a variable number of doubles (an array), and I'm having trouble getting it to function properly.

Thanks all!

Answer 1

I haven't looked at ctypes too much, but try using a numpy array of the right type. If that doesn't just automatically work, they also have a ctypes attribute that should contain a pointer to the data.

Answer 2

To make an array with, say, n doubles:

arr7 = ctypes.c_double * `n` 
x = arr7()

and pass x to your function where it wants a double*. Or if you need to initialize x as you make it:

x = arr7(i*0.1 for i in xrange(7))

and the like. You can loop over x, index it, and so on.