Passing complex numbers into C++

[Andrew Gregory]

I am trying to produce a bit of code to illustrate how complex numbers
can be passed to / from C++ (BCC5.5).  I'm new to this, and finding it
hard going. The following bit of code compiles to complx.pyd  - which
imports into python ok, but if I use the csqr() function it causes a
crash. If anyone can tell me why I would be grateful,
Andrew.

/ Example hand-coded C++ interface to Python

#include <Python.h>
#include <complex.h>
typedef complex<double> dcomplex;


// **** Function (illustrative) ****

Py_complex csqr(Py_complex r)
{
 static Py_complex P;
 dcomplex t = dcomplex(r.real, r.imag);
 t = t*t;
 P.real = real(t);
 P.imag = imag(t);
 return P;
};


// **** Wrapper ****
PyObject *wrap_csqr(PyObject *self, PyObject *args)
{
	Py_complex r, result;
       // r = new Py_complex;
	if (!PyArg_ParseTuple(args,"D:csqr", &r)) return NULL;
	//result = r;
    return Py_BuildValue("D",&r);
};


static PyMethodDef exampleMethods[] =
{
	{ "csqr", wrap_csqr, 1 }, {NULL, NULL}
};


// Must use this for C++
#ifdef __cplusplus
extern "C" {
#endif

void initcomplx()
{
	PyObject *m;
	m = Py_InitModule("complx",exampleMethods);
};

#ifdef __cplusplus
}
#endif