To develop a DLL in VisualC++

usable by VisualBasic

by Jordi Binefa

http://www.binefa.net

To create a new MFC AppWizard(dll) project :

To choose a regular DLL using shared MFC DLL :

The workspace looks like this :

Add a new generic class (myNewClass) :

Add a new member function in the new class (double myNewClass::triple(double num)) :

Type a code in the new function :

double myNewClass::triple(double num)

{

return 3*num;

}

To select the cpp file (pciStyle0Z.cpp) :

Add the new class header at the top of pciStyle0Z.cpp (just below #endif):

#include “myNewClass.h”

Add at the bottom of pciStyle0Z.cpp:

myNewClass nc;

extern "C" double PASCAL EXPORT byThree(double num)

{

AFX_MANAGE_STATE(AfxGetStaticModuleState());

return nc.triple(num);

}

It is declared a new object nc from myNewClass class. The function byThree(double num) returns a double and it is an extern function usable by any programming environment (like VisualBasic or VisualC++).

To call a DLL function from VisualBasic :

Private Declare Function byThree Lib "pciStyle0Z.dll" (ByVal n As Double) As Double

Private Sub Command1_Click()

Dim numero As Double

Dim i As Double

numero = 15

i = byThree(numero)

MsgBox "Triple of " & numero & " is " & i & "."

End Sub