Conference abbott::visual_basic

2495.0. "Problem for calling VC DLL from VB 4.0 32-bit" by DEKVC::DONGWONSHIN () Fri Feb 14 1997 01:43

Does anyone help me for the following problem ?

I have to call DLL file written by Visual C from VisualBasic V4.0
and all have to be programmed with 32bit option because the DLL file should 
call another 32-bit DLL. 
But in execution time, the VB application caused some error as follows;

	"Run time Error "49"
	"Bad DLL calling convention"

I tested the attached sample program but the result was same.

The compiler version is
	VB 4.0 with 32-bit option.
	VC 4.0  respectively.

It's very critical to me because we don't have much time to finish customer 
project.

Hope to hear any kinds of hints or answers.

Thanks in advance.

	/Dong-won

--------------------------------- ATTACHMENT ---------------------------------
* Visual Basic Code.


Attribute VB_Name = "Module1"
Declare Sub plus_data Lib "TEST" (ByVal i As Long)

VERSION 4.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   6555
   ClientLeft      =   1140
   ClientTop       =   1515
   ClientWidth     =   9150
   Height          =   6960
   Left            =   1080
   LinkTopic       =   "Form1"
   ScaleHeight     =   6555
   ScaleWidth      =   9150
   Top             =   1170
   Width           =   9270
End
Attribute VB_Name = "Form1"
Attribute VB_Creatable = False
Attribute VB_Exposed = False
Private Sub Form_Load()
    Dim i As Long
    i = 0
    plus_data (i)
End Sub


*----------------------------------------------------------------------------
* Visual C  code

#include <windows.h>   // required for all Windows applications
#include <stdio.h>

#pragma data_seg("SHARED_SEG")

int gUserCount = 0;

#pragma data_seg(".data")

BOOL InitializeSubsystem()
{
	return TRUE;
}


BOOL InitApp()
{
	return TRUE;
}


BOOL CleanupSubsystem()
{
	return TRUE;
}


BOOL CleanupApp()
{
	return TRUE;
}


BOOL WINAPI DllMain(HANDLE hMoudle,
					DWORD dwReason,
					LPVOID lpReserved)
{
	BOOL bSuccess;
	UNREFERENCED_PARAMETER(hMoudle);
	UNREFERENCED_PARAMETER(lpReserved);

	switch (dwReason){
	case DLL_PROCESS_ATTACH:
		gUserCount++;
		if (gUserCount == 1)
			bSuccess = InitializeSubsystem();
		else
			bSuccess = InitApp();
		break;

	case DLL_PROCESS_DETACH:
		if (gUserCount == 1)
			bSuccess = CleanupSubsystem();
		else
			bSuccess = CleanupApp();
		break;

	}

	return (bSuccess);
}

int plus_data(int data)
{
	data ++;
	return data;
}

 

    Dong-won, this sort of thing has been done by a number of people in
    this conference and, what's more, they've documented it in this
    conference. If you search the conference you will find what you want.
    
    Hint: DIR/tit="DLL" should get you started
    
    Cheers,
    Brian
    PS It is good notes etiquette to do this kind of search BEFORE writing
    a note. That way the conference doesn't get cluttered up with notes
    asking the same question over and over again.