How to call managed C++ methods from Un-managed C++

Question

PLEASE SEE UPDATE BELOW

(RESOLVED) Also I have extended this into a second question here Implement a C# DLL COM File In Unmanaged C++ Program

I have resear

Answer 1

First, your methods receive and return a String^ which is a managed object. Unmanaged code does not know this type, and cannot create such object. So, you will need to wrap the function call such that the function marshal the managed type to something that the unmanaged code can understand.

After that, you can add the DllExport attribute to the managed method, as discussed here.

Answer 2

You could use the cool C++ Marshaling library provided by Microsoft, something like this:

#include "cSharpRiJHarn"
#include "stdafx.h"
#include <string>
#include <stdio.h>
#include "msclr\marshal_cppstd.h" // marshaling library

using namespace cSharpRiJHarn;
using namespace System;
using namespace msclr::interop; // marshaling library

std::wstring Encrypt(std::wstring s)
{
    return marshal_as<std::wstring>(RijndaelLink::encrypt(marshal_as<String^>(s)));
}

std::wstring Decrypt(std::wstring s)
{
    return marshal_as<std::wstring>(RijndaelLink::decrypt(marshal_as<String^>(s)));
}