using System.Windows.Forms;
namespace ManagedNET
{
    public static class CSharpClass
    {
        public static void ShowValue()
        {
            MessageBox.Show("This message is from C# library!", "C# Message Box", MessageBoxButtons.OKCancel);
        }
    }
}

#pragma once
using namespace System;
using namespace System::Reflection;

namespace ManagedCCLI
{
	public ref class DoWork
	{
		public:void ShowCSharpMessageBox()
		{
			ManagedNET::CSharpClass::ShowValue();
			return;
		}
	};
}

__declspec(dllexport) void ShowMessageBox()
{
	ManagedCCLI::DoWork work;
	work.ShowCSharpMessageBox();
}

#pragma once
namespace internal_obj {
	class test_c {
	public:
		void fn_message_show(void);
	};
}

extern "C" __declspec(dllexport) void ShowMessage(void);

#include "stdafx.h"
#include "Step3Rundll32Library.h"
#include <exception>
#include <windows.h>
using namespace std;

_declspec(dllexport) void ShowMessageBox();
void internal_obj::test_c::fn_message_show(void)
{
	try
	{
		ShowMessageBox();
	}
	catch (const std::exception& ex)
	{
		MessageBoxA(NULL, ex.what(), "Error", MB_OK);
	}
	catch (...)
	{
		MessageBoxA(NULL, "Unknown error", "Error", MB_OK);
	}
}

extern "C" __declspec(dllexport) void ShowMessage(void)
{
	internal_obj::test_c tmp;
	tmp.fn_message_show();
}

extern "C" __declspec(dllexport) void ShowMessage(void)

extern "C" __declspec(dllexport) void ShowMessage(void);

extern "C" __declspec(dllexport) void ShowMessage(void)
{
	MessageBoxA(NULL, "Hello world! How are you?", "Error", MB_OK);
}

cmd>rundll32.exe DllTest.dll, ShowMessage

//cmd>rundll32.exe Step3Rundll32Library.dll,_ShowMessage@16
extern "C" __declspec(dllexport) void CALLBACK ShowMessage(HWND hwnd, HINSTANCE hinst, LPSTR lpszCmdLine, int nCmdShow)
{
	internal_obj::test_c tmp;
	tmp.fn_message_show();
}