Calling C++ function from python script

[Pankaj]

The module which i am creating is like

Part A:
1. It does some processing by using python code.
2. The result of this python code execution is written to a text file.
[This part is already compelete]]

Part B:
1. I read a text file which is outputted by above python script in a
C++ program
2. and again output of this c++ code is text file
[This part is as well complete with graph data structure construction
part involved, which i feel can be done in better way in C++ than in
python]

Now i want to integrate this flow.

The communication between part A and part B is by call to a function
present in C++
How should i do that? 
Kindly suggest some ways.

Regards
Pankaj