I want to call the function from a python file from the visual studio 2019. By googling, it looks like I need to use the following function. I added a "Sample.py" in the same place where the exe is stored for the c++ .
int main()
{
Py_Initialize();
// Create some Python objects that will later be assigned values.
PyObject* pName, * pModule, * pFunc, * pArgs = nullptr, * pValue;
pName = PyUnicode_FromString((char*)"Sample");
pModule = PyImport_Import(pName);
pFunc = PyObject_GetAttrString(pModule, (char*)"fun");
pValue = PyObject_CallObject(pFunc, pArgs);
}
In the "Sample.py" which is placed in the same path as the exe of the c++
import matplotlib.pyplot as plt
def fun(): x = [1,2,3]
y = [2,4,1]
plt.plot(1, 2)
And when i run the c++ code, it throws an exception at PyObject_CallObject(pFunc, pArgs); saying Exception thrown at 0x00007FFC54B6F3D2 (python37.dll) in ConsoleApplication9.exe: 0xC0000005: Access violation reading location 0x0000000000000008. Unhandled exception thrown: read access violation. v was nullptr.
I just want to know if im missing any thing in my visual studio setup
Because when i change the sample.py to just following without the #import, it works fine
def fun(): print("Hello from a function")
I changed the following and plotting is ok now !
#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;
}
The plot script in Sample.py is:
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()
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