Easy C++ Project for Python Use

For this tutorial, I will be using Visual Studios 2010 (C++) and Python 2.7 with ctypes.

Let's assume your boss wants a program that performs addition, there are many ways to write this code, but for the sake of this this tutorial, you want to use the python and C++.

• Open Visual Studios
• Follow the steps in creating a project here.
• Give the project a name called additioncpp
• Create a header file called 'additioncpp.h' and enter in the following code:

      int sum(int, int);

•  In the dllmain.cpp file, comment out everything but the '#include "stdafx.h" line
• Now we are ready to write the sum() we defined in the additioncpp.h header file.  Since python like 'C', and not 'C++' we need to use exten "C" around the functions

      #include "stdafx.h"

      #define DLLEXPORT extern "C" __declspec(dllexport)

      DLLEXPORT int sum(int a, int b) {

          return a + b;

       }

• Compile the code and copy the .dll to a new folder
• Create a new .py file and type in the following:
print 'start' 

from ctypes import cdll
mydll = cdll.LoadLibrary(r'PATHTODLL\additioncpp.dll')
print mydll
print mydll.sum
print mydll.sum(1,2)
print 'end'
• You should see an output like this:

>>> 

>>> <_funcptr 0x10ca47b0="0x10ca47b0" at="at" object="object">

>>> 3

>>> end

Enjoy