Call Python code from C++

call_python.cpp

#include <iostream>
#include <pybind11/embed.h> // everything needed for embedding
#include <pybind11/numpy.h>
namespace py = pybind11;

py::array_t<double> create2DArray(int rows, int cols) {
  py::array_t<double> result({rows, cols});
  auto ptr = result.mutable_data();
  /*
  ptr[0] | ptr[1] | ptr[2]
  ptr[3] | ptr[4] | ptr[5]
  */
  ptr[0] = 1.0;
  ptr[1] = 2.0;
  ptr[2] = 3.0;
  ptr[3] = 4.0;
  ptr[4] = 5.0;
  ptr[5] = 6.0;
  return result;
}

int main() {
  py::scoped_interpreter guard{}; // start the interpreter and keep it alive

  try
  {
    py::print("Hello, World!"); // use the Python API

    py::module_ calc = py::module_::import("calc");
    py::array_t<double> arrayA = create2DArray(2, 3);
    py::array_t<double> arrayB = create2DArray(2, 3);
    py::dict res = calc.attr("add_np")(arrayA, arrayB);
    auto array = res["result"].cast<py::array_t<double>>();
    auto answer = res["answer"].cast<int>();
    std::cout << "Answer: " << answer << std::endl;
    
    for (size_t i = 0; i < 6; i++)
    {
      std::cout << array.mutable_data()[i] << std::endl;
    }
  }
  catch(const py::error_already_set& e) {
    PyErr_Print();
    std::cerr << "Python Error: " << e.what() << std::endl;
  }
  catch(const std::exception& e)
  {
    std::cerr << "C++ Exception: " << e.what() << std::endl;
  }
}