Python file to run from C++ code

Question

I am using Python 3.3. I am using C++ Qt code and embedding python into it. I want to execute one python file using C Python API in Python 3.

Below is sample code i am using to read the file and execute using Qt.

FILE *cp = fopen("/tmp/my_python.py", "r");
if (!cp)
{        
    return;
}

Py_Initialize();

// Run the python file
#ifdef PYTHON2
PyObject* PyFileObject = PyFile_FromString("/tmp/my_python.py", (char *)"r");
if (PyRun_SimpleFile(PyFile_AsFile(PyFileObject), "/tmp/my_python.py") != 0)
    setError(tr("Failed to launch the application server, server thread exiting."));

#else
int fd = fileno(cp);
PyObject* PyFileObject = PyFile_FromFd(fd, "/tmp/my_python.py", (char *)"r", -1, NULL, NULL,NULL,1);
if (PyRun_SimpleFile(fdopen(PyObject_AsFileDescriptor(PyFileObject),"r"), "/tmp/my_python.py") != 0)
    setError(tr("Failed to launch the application server, server thread exiting."));
#endif
Py_Finalize();

For Python2 everything is working fine. But for python3(#else part) is not working under windows. Application is getting crashed. I do not want to read line by line and execute.

Can anyone give me guidance how to execute python file in C++ application using Python3 ? Some pseudo code or link will be helpful.

Thanks in Advance.

Why are you not just passing cp instead of trying to be clever? — Ignacio Vazquez-Abrams
– Ignacio Vazquez-Abrams, Commented Jul 15, 2016 at 11:55
You mean to say to call "if (PyRun_SimpleFile(cp, "/tmp/my_python.py")) right? This also i have tried but same result. — Neel
– Neel, Commented Jul 15, 2016 at 11:57

Silas Parker · Accepted Answer · 2016-07-15 12:37:55Z

1

The following test program works fine passing the FILE pointer in directly for me.

runpy.c

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

int main(int argc, char** argv)
{
  if (argc != 2)
  {
    printf("Usage: %s FILENAME\n", argv[0]);
    return 1;
  }
  FILE* cp = fopen(argv[1], "r");
  if (!cp)
  {
    printf("Error opening file: %s\n", argv[1]);
    return 1;
  }

  Py_Initialize();

  int rc = PyRun_SimpleFile(cp, argv[1]);
  fclose(cp);

  Py_Finalize();  
  return rc;
}

Compiled on Fedora 23 with:

g++ -W -Wall -Wextra -I/usr/include/python3.4m -o runpy runpy.c -lpython3.4m

answered Jul 15, 2016 at 12:37

Silas Parker

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