Pass a managed C++ pointer from VBA to a C++ DLL RRS feed

  • Question

  • I'm not a programmer, just an enthusiastic hacker.  I’m trying to write a centralised DLL that I can access from both the VBA environment within Visio as well as from another C++ development.  I’m trying to get the first bit to work.  What I want to do is to be able to pass a Visio shape to the DLL where I can process it and return it.  I’ve written the following C++ development:

    Configuration Type                                Dynamic Library (.dll)

    Use of MFC                                            Use Standard Windows Libraries

    Use of ATL                                             Not Using ATL

    Character Set                                        Use Unicode Character Set

    Common Language Runtime support   Common Language Runtime Support (/clr)

    Whole Program Optimisation                 No Whole Program Optimization

    The DLLver8.cpp file looks like this:

    // DLLver8.cpp
    //This is the main DLL file.
    #include "stdafx.h"
    #include "DLLver8.h"
    double __clrcall AddDouble(double a, double b){
    	return a+b;
    bool __clrcall AddText(Visio::Shape^ InputShape){
    		InputShape->Text = "DLL Return";
    		return true;
    		return false;

    The DLLver8.h file looks like this:

    // DLLver8.h
    #pragma once
    using namespace System;
    double __clrcall AddDouble(double a, double b);
    bool __clrcall AddText(Visio::Shape^ InputShape);

    The DLLver8.def file looks like this:

    LIBRARY	"DLLver8"

    The VBA code looks like this in a module:

    Option Base 0
    Option Explicit
    Public Declare Function AddDouble Lib "C:\Users\nortj0\Documents\Visual Studio 2008\Projects\DLLver8\Debug\DLLver8.dll" (ByVal a As Double, ByVal b As Double) As Double
    Public Declare Function AddText Lib "C:\Users\nortj0\Documents\Visual Studio 2008\Projects\DLLver8\Debug\DLLver8.dll" (ByRef InputShape As Visio.Shape) As Boolean

    And this in the ThisDocument

    Sub Object(VisioShape As Visio.Shape)
    Dim Test As Double
    Dim TestBool As Boolean
    Test = AddDouble(5.1, 6.2)
    VisioShape.Text = "Pre DLL"
    TestBool = AddText(VisioShape)  'Crash and burn here!!!
    End Sub

    The problem I have is that when I run the VBA code the code crashes to the extent that Visio shuts down.  It fails at the “TestBool = AddText(VisioShape)” statement in the VBA code. 

    If I remove the references to the Visio Shape in both the DLL and in the VBA then it works fine, just returning a Boolean true or false.  The AddDouble works just fine too, so I’m hurting something somewhere with this Visio.Shape.

    Can anyone help me with how to pass a Visual C++ pointer (^) reference from VBA to C++?

    • Moved by Elegentin Xie Monday, July 15, 2013 7:40 AM from Visual C++, to a more appropriate forum
    Wednesday, July 10, 2013 12:31 PM

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