Ndtyjky

I cmake a project and want to get numpy array in C++ project. I can get the right nums but it reports read access violation. Here is my python code named main.py

import numpy as np

import tensorflow as tf



class PyInterface(object):

    def __init__(self):

        self.X = None

        self.Y = None



    def generate_np_uint8(self):

        np_array = np.random.randint(low=0, high=255, size=(2,2,2),dtype=np.uint8);

        print("Python, uint8:", np_array)

        return np_array



    def generate_np_float32(self):

        np_array = np.random.rand(2,2,2).astype(np.float32)

        print("Python, float:", np_array)

        return np_array





if __name__ == '__main__':

    py = PyInterface();

    py.generate_np_uint8();

    py.generate_np_float32();

Here is my C++ code for extend python

public:

float * CppPythonHandler::get_float() {

    return generate_np_float32();

}

private:

float * CppPythonHandler::generate_np_float32() {

    const int ND{3};

    float *c_out = new float[8];

    PyArrayObject *np_ret;

    PyObject* np_array = PyObject_CallMethod(interface, (const char*)"generate_np_float32", NULL, NULL);

    if (np_array) {

        np_ret = reinterpret_cast<PyArrayObject*>(np_array);

        if (PyArray_NDIM(np_ret) != ND) {

            std::cout << "Function returned with wrong dimension" << std::endl;

            Py_DECREF(np_array);

            Py_DECREF(np_ret);

            return c_out;

        }

        c_out[0] = *((float *)PyArray_GETPTR3(np_ret, 0, 0, 0));

        c_out[1] = *((float *)PyArray_GETPTR3(np_ret, 0, 0, 1));

        c_out[2] = *((float *)PyArray_GETPTR3(np_ret, 0, 1, 0));

        c_out[3] = *((float *)PyArray_GETPTR3(np_ret, 0, 1, 1));

        c_out[4] = *((float *)PyArray_GETPTR3(np_ret, 1, 0, 0));

        c_out[5] = *((float *)PyArray_GETPTR3(np_ret, 1, 0, 1));

        c_out[6] = *((float *)PyArray_GETPTR3(np_ret, 1, 1, 0));

        c_out[7] = *((float *)PyArray_GETPTR3(np_ret, 1, 1, 1));

        for (int i = 0; i < 8; ++i) {

            std::cout << c_out[i] << " ";

        }

        std::cout << std::endl;

        Py_DECREF(np_ret);

        Py_DECREF(np_array);

        return c_out;

    }

    else{

        PyErr_Print();

        Py_DECREF(np_array);

        Py_DECREF(np_ret);

        return c_out;

    }

}

Here is my main.cpp

static int numargs=0;



static PyObject*

emb_numargs(PyObject *self, PyObject *args)

{

    if(!PyArg_ParseTuple(args, ":numargs"))

        return NULL;

    return PyLong_FromLong(numargs);

}



static PyMethodDef EmbMethods = {

    {"numargs", emb_numargs, METH_VARARGS,

     "Return the number of arguments received by the process."},

    {NULL, NULL, 0, NULL}

};



static PyModuleDef EmbModule = {

    PyModuleDef_HEAD_INIT, "emb", NULL, -1, EmbMethods,

    NULL, NULL, NULL, NULL

};



static PyObject*

PyInit_emb(void)

{

    return PyModule_Create(&EmbModule);

}



int main(int argc, char *argv) {

    if (argc < 1) {

        fprintf(stderr,"Usage: call pythonfile funcname [args]n");

        return 1;

    }



    numargs = argc;

    PyImport_AppendInittab("emb", &PyInit_emb);



    Py_Initialize();        // initialize python interpreter

    PyRun_SimpleString("import sys");

    PyRun_SimpleString("if not hasattr(sys, 'argv'):n    sys.argv=['']");

    PyRun_SimpleString("sys.path.insert(0, "./")");

    PyRun_SimpleString("sys.path.insert(0, "./venv/Lib")");

    PyRun_SimpleString("sys.path.insert(0, "./venv/Lib/site-packages")");



    // instance cpp interface object

    CppPythonHandler * pInter = new CppPythonHandler("main", "PyInterface");

    // unsigned char * np_uint8 = pInter->get_uint8();

    float * np_float = pInter->get_float();



    std::cout<<"End test"<<std::endl;

    // delete pInter;



    if (Py_FinalizeEx() < 0) {

        std::cout << "Fails to release" << std::endl;

        return 120;

    }

    system("pause");

    return 0;

}

by the terminal I can see that I can get the right value from python script

from the call stack I know it corrupts in PyObject_Alloc

but I still don't what exactly the problem is. can anyone tell me

EDIT1：
Here is my constructor

CppPythonHandler::CppPythonHandler(const char* pModuleName, const char* pClassName) {

    interfaceModule = NULL;

    interfaceClass = NULL;

    interface = NULL;

    interfaceModule = PyImport_ImportModule(pModuleName);

    if (interfaceModule == NULL) {

        PyErr_Print();

        fprintf(stderr,"Fails to import the module.n");

        Py_DECREF(interfaceModule);

    }

    else{

        // import interface class

        interfaceClass = PyObject_GetAttrString(interfaceModule, pClassName);

        if (interfaceClass && PyCallable_Check(interfaceClass)) {



            // NULL represents no args

            interface = PyObject_CallObject(interfaceClass, NULL);

            Py_DECREF(interfaceClass);

            Py_DECREF(interfaceModule);

            if(interface == NULL){

                fprintf(stderr,"Fails to instance interface.n");

                Py_DECREF(interface);

            }

            std::cout<<"Initailization done"<<std::endl;

        }

        else{

            if (PyErr_Occurred())

                PyErr_Print();

            fprintf(stderr,"Fails to import the class.n");

            Py_DECREF(interfaceClass);

            Py_DECREF(interfaceModule);

        }

    }

}

interfaceModule, interfaceClass and interface are private PyObject*

EDIT2:
here is the local parameters of PyObject_Alloc