Python import dll

You've tagged the question ctypes and so it sounds like you already know the answer.

The ctypes tutorial is excellent. Once you've read and understood that you'll be able to do it easily.

For example:

>>> from ctypes import *>>> windll.kernel32.GetModuleHandleW(0)486539264

And an example from my own code:

lib = ctypes.WinDLL('mylibrary.dll')#lib = ctypes.WinDLL('full/path/to/mylibrary.dll')func = lib['myFunc']#my func is double myFunc(double);func.restype = ctypes.c_doublevalue = func(ctypes.c_double(42.0))

I'm posting my experience. First of all despite all the hard work that take me to put all pieces together, importing a C# dll is easy. The way I did it is:

1) Install this nuget package (i'm not owner, is just very useful) in order to build a unmanaged dll: https://sites.google.com/site/robertgiesecke/Home/uploads/unmanagedexports

2) Your C# dll code is like this:

using System;using RGiesecke.DllExport;using System.Runtime.InteropServices;public class MyClassName{   [DllExport("MyFunctionName",CallingConvention = CallingConvention.Cdecl)]   [return: MarshalAs(UnmanagedType.LPWStr)]   public static string MyFunctionName([MarshalAs(UnmanagedType.LPWStr)] string iString)   {       return "hello world i'm " + iString   }}

3) Your python code is like this:

import ctypes#Here you load the dll into python MyDllObject = ctypes.cdll.LoadLibrary("C:\\My\\Path\\To\\MyDLL.dll")#it's important to assing the function to an objectMyFunctionObject = MyDllObject.MyFunctionName#define the types that your C# function returnMyFunctionObject.restype = ctypes.c_wchar_p#define the types that your C# function will use as argumentsMyFunctionObject.argtypes = [ctypes.c_wchar_p]#That's it now you can test itprint(MyFunctionObject("Python Message"))

c-types NOTE!

Using WinDLL (and wintypes, msvcrt) is windows specific imports and does not always work, even on windows! The reason is that it depends on your python installation. Is it native Windows (or using Cygwin or WSL)?

For ctypes, the more portable and correct way is to use cdll like this:

import sysimport ctypesfrom ctypes import cdll, c_ulongkFile = 'C:\\Windows\\System32\\kernel32.dll'mFile = 'C:\\Windows\\System32\\msvcrt.dll'try:     k32    = cdll.LoadLibrary(kFile)    msvcrt = cdll.LoadLibrary(mFile)except OSError as e:    print("ERROR: %s" % e)    sys.exit(1)# do something...