reading a global variable of python in c

Question

I am trying to learn how to use the Python/C API correctly - all I actually need to do is to read a global variable (in my case dictionary - but I\'m starting with a simple

Answer 1

I know this question is from long ago, but this is for others who stumble across this while googling.

OP says his code doesn't work, but ironically, his code worked for me better than other examples.(Thanks, @et_l)

So, the answer - how to access python variables from C - for the OP's code (with the main module code OP wrote);

#include <stdio.h>
#include <Python.h>

int main () {
  Py_Initialize();
  PyRun_SimpleString("var1 = 1");
  PyRun_SimpleString("var2 = ['bla', 'blalba']");
  PyRun_SimpleString("var3 = {'3' : 'Three', '2' : 'Two', '1' : 'One', '0' : 'Ignition!'}");
  PyRun_SimpleString("print('end of file - tryStuff!!')");

  PyObject *mainModule = PyImport_AddModule("__main__");
  PyObject *var1Py = PyObject_GetAttrString(mainModule, "var1");
  int c_var1 = PyLong_AsLong(var1Py);
  printf("var1 with C: %d\n", c_var1);

  Py_Finalize();
  return 0;
}

Answer 2

You should call PyObject_GetAttrString on the result of PyImport_ImportModule. I have no idea why you think that the __main__ module should define that variable:

PyObject *mod = PyImport_ImportModule("tryStuff");
PyObject *var1Py = PyObject_GetAttrString(mod, "var1");

You should also add the check on the results, since PyImport_ImportModule can return NULL when the import fails.