Calling exported C functions (DLL) in Visual Basic

[buzznick]

Hi, I'm writing a DLL in C/C++ that needs to export a couple of functions to be used by a Visual Basic program. However, we're having some trouble getting the Visual Basic to read the exported C functions.

They are very simple functions, eg:

extern "C" __declspec(dllexport)
void test_get_string(LPSTR str)
{
strcpy(str,"Hello World!");
}

extern "C" __declspec(dllexport)
UINT test_get_number(void)
{
return 123456;
}

The problem is that I don't know VB at all but that's all my client uses. He says I'm not exporting the functions correctly in the DLL because he's getting a "453" error (whatever that is!).

It was my understanding that simple C functions (as above) inside a DLL could be called from VB no problem.

Is it something I did wrong or is the client doing something wrong? Either way, how do I fix it?

Many thanks!

 

[Hypetia]

---------------------------
Microsoft Visual Basic
---------------------------
Run-time error '453':

Specified DLL function not found
---------------------------
OK Help
---------------------------

Error 453 indicates that the function your client is calling is not exported by that name. You need to verify that your client is calling the correct function name as exported by your DLL.

You can also use Dependency Walker to examine the export table of your compiled DLL.

 

[LazyMe]

Probable something you already did, but I'll try it anyway:

Did you actually export the functions by name? Did you, for instance link a module definition file? Something like:

LIBRARY "YourDLL.DLL"

EXPORTS
YourFunction1 @1 PRIVATE
YourFunction2 @2 PRIVATE


Greetings,
Rick

 

[buzznick]

Hi Guys,

Thanks for that. I did manage to fumble through a bit of VB and get this working after discovering this link:

http://support.microsoft.com/default.aspx?scid=KB;en-us;q106553

Thanks,
Nick