Pointer to incomplete Class type is not allowed

First, let me say I do know there exist 1000 of this question on google. I just haven't found one that helped me.

Basically my program has 3 layers: 1) VB.net DLL --> 2) C++ / CLR uses the managed part to allow it to be used by the next --> 2) unmanaged C++

I get an error in my console test app... So here's the code

VB.net:

Code:

---

Public Class Add
    public function Adding(Byval x as Double, Byval y as Double) as Integer
          return x+y
    end function
end class

---

C++/CLR

header AddingWrapper.h

Code:

---

#include "stdafx.h"
#include <msclr\auto_gcroot.h>
#using "Class1.dll"
class AddingWrapperPrivate;


class __declspec(dllexport) AddingWrapper {

private: AddingWrapperPrivate* _private;
public: AddingWrapper();
                int Adding(double* x, double* y);
                ~AddingWrapper();

};

---

CPP --> AddingWrapper.cpp

Code:

---

#include "stdafx.h"

#include "AddingWrapper.h"

#using "Class1.dll"
#include <msclr\auto_gcroot.h>
using namespace System::Runtime::InteropServices;
       
class AddingWrapperPrivate {
public: msclr::auto_gcroot<Add^> add;
};

 AddingWrapper::AddingWrapper()
        {
                _private = new AddingWrapperPrivate();
                _private->add = gcnew Add();
        };
  int AddingWrapper::  Adding(double* x, double* y) {
                return _private->add->Adding(*x, *y);
        };
        AddingWrapper::~AddingWrapper()
        {
                delete _private;
        };

---

Finally, where the error occurs:

Test.cpp console app

Code:

---

#include "stdafx.h"
#include "AddingWrapper.h"
#include <iostream>
int main()
{
        double x = 3;
        double y = 3;
        AddingWrapper* add;
        *add->Adding(x, y);  //pointer to incomplete class type is not allowed
        std::cout << "here is the result";
       
    return 0;
}

---

Any insight on how I could fix this thing? I'm about to throw it out the window

As this is mainly a c++/cli question, I suggest you post this to the c++ cli forum here http://forums.codeguru.com/forumdisp...ed-C-and-C-CLI

This forum is for non Microsoft Visual Studio c++ issues.

[moderator could you move please]

My bad, I just saw console application, so I posted here!

However, the forum seems inactive :/

It's not that active, but when a new thread is started there is usually a reply fairly quickly. :)

[moved from C++ (Non Visual C++ Issues) forum]

Actually, although a C++/CLI wrapper is involved, I'd say this is a native C++ question, at least at this point.

The reason for the error message you're referring to lies in your AddingWrapper.h: There you forward-declare a class named AddingWrapperPrivate, but only actually define it at the beginning of AddingWrapper.cpp. And using a pointer to or trying to instantiate that class is an error anywhere outside AddingWrapper.cpp. There's entirely no need for that class anyway: Simply make your auto_gcroot variable a direct member of AddingWrapper.

Also, you forgot to new a wrapper instance in your demo main(), the * when you reference it is superfluous (it is implied by the ->) and you need to pass the two parameters prefixed by & since they're pointers (what they don't need to be). Finally, there's no need to refer to the wrapper via pointer in this scenario - simply make the wrapper an ordinary local instance variable of main() -, or, if you're using the pointer, you need to delete it before leaving main().