Calling Python-3 function in C

Question

I am trying to call Python code in C with this code:

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

int main()
{
    PyObject* pInt;

    Py_Initialize();

    PyRun_SimpleString("print('This is Python in C')");

    Py_Finalize();

    printf("\n");
    return 0;
}

and have tried compiling it with this command:

gcc python_test_in_c.c

However it returns an error returns saying:

undefined referance to `__imp __Py_Initialise`
undefined referance to `__imp__PyRun_SimpleSringFlags`
undefined referance to `__imp__Py_Finalise`
collect2.exe:  error: ld returned 1 exit status

What is going wrong? How can I fix this?

Any help would be appreciated

P.S I am not sure, but could this be something to do with the fact I copied the Python 'include' file (containing Python.h) in the include file for MinGW located at C:/MinGW

UPDATE: I have now learned this is ok to do but considered bad practice.

Please edit the title! It does not make any sense and is just missleading. You don't "embed Python code in C". You call simply functions from the Python C API. That's not different from any other library. — too honest for this site, Jul 26 '17 at 19:52
@Olaf technically this looks like embedding to me, see `PyRun_SimpleString("print('This is Python in C')");`. It is embedding via an library API. — Ajay Brahmakshatriya, Jul 27 '17 at 05:47
@AjayBrahmakshatriya: The title is completely different. And this is not really embedding, but simply passing a string to a library function. It is not different from e.g. `fopen` Where no one would say the file contents is embedded into the C code. In fact the question is not even related to Python or possibly C, but linking and there is no information given by the user to really solve it (jut rough guesses). — too honest for this site, Jul 27 '17 at 10:51
@Olaf The python 2.7.13 documentation refers to this as Very High Level Embedding. See this [webpage](https://docs.python.org/2/extending/embedding.html) — Xantium, Jul 29 '17 at 19:36
@Simon: It could call it "christianising". Doesn't change the fact you simply call a normal C functions and use a library. I already said: learn to abstract concepts. — too honest for this site, Jul 29 '17 at 19:48

score 2 · Accepted Answer · answered Jul 26 '17 at 20:04

2

You are not linking with the python library...

try:

gcc python_test_in_c.c -lpython3.6m

change 3.6 to your version of choice...

answered Jul 26 '17 at 20:04

Yoav Glazner

7,936
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I have tried this but it returns an error saying it cannot find lpython3.6m the path on my computer for python is C:\Users\Simon\AppData\Local\Programs\Python\Python36-32 – Xantium Jul 26 '17 at 20:14
1

try to add -L C:\Users\Simon\AppData\Local\Programs\Python\Python36-32\libs – Yoav Glazner Jul 27 '17 at 06:10
Solved it ! Compiled it with gcc python_test_in_c.c -lpython36 added the python36 dll along with the exe and it works. The . (dot) and m in python3.6m generates an error, remove these and it works.Thanks for the help everyone. – Xantium Jul 27 '17 at 11:14

Calling Python-3 function in C

1 Answers1