Creating a DLL using C++
For creating a DLL in C++, I was used cl.exe, which comes with .net framework. For the implementation I just wrote simple C++ file.(Simple.cpp)

#include <iostream>

extern "C" __declspec(dllexport) char* Hello();
char* Hello()
{
	return "Hello world";
}

I think this is pretty much clear.The extern “C” __declspec(dllexport) allows generate export names automatically. For more details :Exporting from a DLL Using __declspec(dllexport)(MSDN)

After creating this Simple.cpp file, go to Visual Studio Tools > Visual Studio 2008 Command Prompt. Go to the location where you have stored the Simple.cpp file and for compiling and linking C++ file you can use “cl.exe /LD Simple.cpp”.(For more details about cl.exe options checkout : Compiler Options Listed Alphabetically(MSDN) It will compile and Link, and gives a DLL as output.

Consuming a C++ library in C#
When I try to add the DLL by Add Reference, Visual Studio will not allows to add C++ library as Reference. So I tried it with Interop option, by using DLLImportAttribute.

[DllImport(@"D:\Simple.dll", EntryPoint = "Hello")]
public extern static string Hello();

Then you can call this function in C# like the following

private void button1_Click(object sender, EventArgs e)
{
            MessageBox.Show(Hello());
}

It will display a Messagebox with “Hello World”. Thats it you consumed a C++ DLL in C#.

Issue in the implementation

1. I can’t use the DllImport function without the full location. To avoid this I tried to Register the DLL using RegSvr32.But I got some error from RegSvr like this.

The module “D:\Simple.dll” was loaded but the entry-point DllRegisterServer was not found.

Make sure that “D:\Simple.dll” is a valid DLL or OCX file and then try again.

I still exploring the things, I will update once I got the solution for this. Happy Coding

Here is the code to call word macros from VB.Net.

Dim WordApp As New Microsoft.Office.Interop.Word.Application
CType(WordApp, Object).GetType().InvokeMember("Run", Reflection.BindingFlags.Default Or Reflection.BindingFlags.InvokeMethod, Nothing, CType(WordApp, Object), New Object() {"helloworld"})

In the code, helloworld is the macro name.Or you can simply call WordApp.Run("helloworld") will also works fine.

You can also refer link from Microsoft
http://support.microsoft.com/kb/306683