One more good news

Code:
#include <iostream>
#include "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\include\Python.h"

using namespace std;

int main(int)
{
    Py_Initialize();//-Initialize python interpreter
    if (!Py_IsInitialized())
    {
        PyRun_SimpleString("print 'inital error!' ");
        return -1;
    }
    //PyRun_SimpleString("print 'inital ok! ");
    PyRun_SimpleString("import sys");//--It is equivalent to the import sys statement in python, sys is to deal with the interpreter
    PyRun_SimpleString("sys.path.append('./')"); //Specify the directory where pytest.py is located
    PyRun_SimpleString("sys.argv = ['python.py']");
    PyObject* pName = NULL;
    PyObject* pMoudle = NULL;//---Store the python module to be called
    PyObject* pFunc = NULL;//---Store the function to be called
    pName = PyUnicode_FromString("Sample"); //Specify the file name to be imported
    pMoudle = PyImport_Import(pName);//--Using the import file function to import the helloWorld.py function
    if (pMoudle == NULL)
    {
        PyRun_SimpleString("print 'PyImport_Import error!' ");
        return -1;
    }
    pFunc = PyObject_GetAttrString(pMoudle, "fun");//--Find the hello function in the python reference module helloWorld.py
    PyObject_CallObject(pFunc, NULL);//---Call hello function

    Py_Finalize();//---Clean up the python environment and release resources
    return 0;
}
Sample.py

Code:
import matplotlib.pyplot as plt
import numpy as np
def fun():
    x = np.arange(-5, 5, 0.02)
    y = np.sin(x)
    plt.axis([-np.pi, np.pi, -2, 2])
    plt.plot(x, y, color="r", linestyle="-", linewidth=1)
    plt.show()
I changed the function with one of the google suggestions and it finally works !!!

Thanks a lot Arjay for your inputs helped me