Embedding Python app in c app

Question

I am on integration of a c library to python application. and i need to pass a list of variables from python size to a wrapper of C lib(which i am calling) just for understanding, i have written a small program:
After loading shared lib in python app. In Python side:

 c_args = [5,6]
 PyPrintVal(c_args)

In C side:

PyPrintVal(PyObject *c_args)
{
 int i=0;
 int j=0;
 printf("In eINoiseRemoval\n");
 if (!PyArg_ParseTuple(c_args, "ii", &i,&j))
 { fprintf(stderr, "error in parsing\n");
 return -1;
 }
 printf(i1=%d j=%d\n, i,j)
}

then I am getting segmentation fault ? Is there anything left?
for that i am looking http://docs.python.org/2/extending/extending.html#a-simple-example

but not getting any answer. Thanks

• falsetru: Call PyPrintVal(*c_args).
• falsetru: I mean: call PyPrintVal(*c_args) in python side.
• Javed: right ctypes. from ctypes import * ; handle=CDLL( "example.so" ); PyPrintVal=handle.PyPrintVal; PyPrintVal.argtypes = [py_object]
• Javed: thanks falsetru, done !! by PyList_GetItem(,) call.

Answer 1

You can use gdb to find out exactly where this segfault is:

$ gdb python
......
> set args my_python_script.py
> run
.......
Segmentation Fault
> where

This will give you a stack trace and point you to the exact location of the segfault.

• Javed: and now it looks like this i = PyInt_AsLong(PyList_GetItem(c_Arg, 0)); i = PyInt_AsLong(PyList_GetItem(c_Arg, 0)); printf(i=%d j=%d\n, i,j); output i=5 j=6