How to call functions from a VB6 dll ??

[Jason Jacob]

To all,

How can I make function calls from a VB6 dll in c# ???
What are type libraries ?? Is it the XXX.lib file generated by VB6 ??

I've tried using P/Invoke to call the dll, but IO Exception occurs
(..... can't find the function's Entry Point ....)

Thanks

From Jason (Kusanagihk)

 

[Guest]

hi,
Try to use DllImport Attribute to achive.

 

[José Joye]

Have a look to the following article:

http://www.codeproject.com/dotnet/nettocom.asp?target=vb|ccw

José

 

[Willy Denoyette [MVP]]

The only way to call into C# from VB6 or the other way arround is through
COM interop.
Search the MSDN docs for "COM Interop" and you will find a tutorial that
explains very well what should be done.

Willy.

 

[Ignacio Machin \( .NET/ C# MVP \)]

HI Jason,

IIRC with VB6 you could only create COM dlls, no windows native DLL , you
use P/Invoke to interact with native dll, that's why you are getting the
"entry point not found exception"

Take a look at the
http://msdn.microsoft.com/library/d...ml/vaconIntroductionToCOMInteroperability.asp

It's for Vb.net but i works the same for a C# project

Cheers,

 

[Jason Jacob]

To all,

Thanks for the links first, but I want to clarify 1 thing.
If I'm using .Net to write a class library (Dll), then all I have to
do is to import that dll under "References", then I can instantiate
the dll object and perform the functions (ie. treat it as an object).
Is that right? It worked quite well to me.

But if the dll is written by unmanaged code (eg. VB6), then I must
somehow create a type library for that dll first (but how ???),
hopefully, if I could generate the required type library file, I can
import and use it just like the above way ??? (I don't know yet, since
I don't know how to generate the type library)
Or, I should use P/Invoke instead ???

Thanks

From Jason (Kusanagihk)

 

[Willy Denoyette [MVP]]

Inline ***
Willy.

To all,

Thanks for the links first, but I want to clarify 1 thing.
If I'm using .Net to write a class library (Dll), then all I have to
do is to import that dll under "References", then I can instantiate
the dll object and perform the functions (ie. treat it as an object).
Is that right? It worked quite well to me.

*** Right.

But if the dll is written by unmanaged code (eg. VB6), then I must
somehow create a type library for that dll first (but how ???),

*** VB6 merges the typelib info into the DLL, so you only need to reference
the DLL as a COM DLL.

 

[Jason Jacob]

to all,

Thanks! It works well now.
But one last question, from the MSDN link supplied earlier, I've read
something like a "Wrapper" class to wrap up the unmanaged dll....
What does that mean ?? (sounds complicated)

Thanks again!

From Jason (Kusanagihk)

 

[Jason Jacob]

To all,

I've found a link explaining all the wrapper related classes and
concepts at :

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconcomwrappers.asp

Sounds like you don't need to handle wrappers directly, since the
VS.Net should generate the them when needed.

From Jason (Kusanagihk)

 

[Richard Johns]

Jason,
What was your resolution for this problem? I am doing the exact
samething right now. Thank you for your help


Richard

 

[Jason Jacob]

To Richard,

Please read the 6th thread.
Actually, just include the dll to your project through "Reference -->
add reference --> browse for the dll......."

everything should be working as long as that dll doesn't contain
functionalities that your WinCE/PocketPC Platform doesn't support at
all.

From Jason (Kusanagihk)