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fromm VB to a DLL written in Visual C++.

Posted on 2005-03-16
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Last Modified: 2010-05-02
What I need to know is how to pass a string type, by reference and as
a parameter, fromm VB to a DLL written in Visual C++. Right now I am
trying it and I am not getting values back from the dll even though I
get the values when I either debug the dll or run it from a driver app
compiled in C. The C app was compiled as a standard DLL. I also tried
it as a COM DLL and I got the same issue.

The problem is that I have a VB client app accessing a Visual C++
standard DLL. The client app needs to send a string values to the dll
and have the dll update these values for later use by the client app.

I can contact the dll and get the values it's just that when it gets
back to the client app it is gibberish. I have tried just sending the
string on way and I realise that C++ arrays and VB strings have
compatability issues.
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Question by:struggling_coder_3203
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3 Comments
 
LVL 32

Accepted Solution

by:
Erick37 earned 1500 total points
ID: 13557224
=Short version=
How To Pass a String Between Visual Basic and Your C DLL
http://support.microsoft.com/default.aspx?scid=kb;en-us;187912

=Long Version=
How to pass arrays and strings between Visual Basic and C functions or between Visual Basic and C++ functions by using Visual Basic 6.0
http://support.microsoft.com/default.aspx?scid=kb;en-us;205277
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LVL 7

Expert Comment

by:wtconway
ID: 13562507
How are you referencine your DLL?

Are you doing it thru References from the Project Menu or are you referencing as you would an API?
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Author Comment

by:struggling_coder_3203
ID: 13569882
Referencing as I would an API. Most of my testing was done when I
compiled the C++ project as a standard DLL. So I accessed it as I
would windows API.

I also tested it, though not as thoroughly, when I compiled the
project as a COM dll. I think I still had similar issues. Of course at
that time I made a reference from the Project menu.

Regards
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