[Anonymous]

I need to update a VB caption, with textual information - detailing
progress of processing being carried out in a C DLL.

Basically, I want my C function to be able to write messages back to VB,
which will then display the message in a label.

C prototype will be something like this:

#ifdef __cplusplus
extern "C" {
#endif

void writeGUIMessage(const char* msg);

#ifdef __cplusplus
};
#endif


How may I do this?

Archived from group: microsoft>public>vb>enterprise

[Ralph]

"Anonymous" wrote in message@bt.com...
> I need to update a VB caption, with textual information - detailing
> progress of processing being carried out in a C DLL.
>
> Basically, I want my C function to be able to write messages back to VB,
> which will then display the message in a label.
>
> C prototype will be something like this:
>
> #ifdef __cplusplus
> extern "C" {
> #endif
>
> void writeGUIMessage(const char* msg);
>
> #ifdef __cplusplus
> };
> #endif
>
>
> How may I do this?

If you have your heart set on using Window Messages to communicate you may
find what follows poor advice. So if that's true you can stop reading now.

(By the way you are apparently using C++, not "C")

The easiest solution is to wrap your C++ code in an ActiveX component. If
using VC++ you can use ATL to simplify the process. Then expose a Event that
VB can use to update the Label.

In your VB code you would have...
Private WithEvents oJunk As MyDll
....
Private Sub oJunk_GUIMessage(ByRef sMessage As String)
Form1.Label1.Caption = sMessage
End Sub

I find using an ActiveX component far simpler that piddling around with
Hooks and such, and the ATL Wizard will manage most of the work for you.

-ralph