Need a method to send byte arrays from Unmanaged C DLL to VB

[Vince Castellano]

Hello,

What is the proper way to send byte arrays (or strings for that
matter), from a C DLL to VB? I have tried by prototyping the call in VB
with ByRef Byte[] as a parameter, then treating it in C as a pointer to
unsigned char, and then I tried a memcpy, as well as using pointer
arithmetic to copy over byte per byte.

However, everything I try causes a runtime error regarding the stack
being unbalanced. I am sure I am doing this all wrong, however there
has to be a way to get a piece of memory from C into VB, and I just
can't find it, nor any information on it.

If this is not the proper group, please point me in the right
direction.

Thanks for any help,
Vince

 

[TDC]

Assuming you are in .NET and calling a C dll, you actually have a
number of options.

If you want bytes, then declare it as a ByVal byte array. Just be sure
you allocate the space (using redim for example) in the .NET side
before calling the C routine.

For text data, you can use a StringBuffer instead of a byte array.

HTH,
Tom

PS - The interop group is probably a better fit for this kind of
question in the future

 

[Mattias Sjögren]

Vince,

What is the proper way to send byte arrays (or strings for that
matter), from a C DLL to VB? I have tried by prototyping the call in VB
with ByRef Byte[] as a parameter, then treating it in C as a pointer to
unsigned char, and then I tried a memcpy, as well as using pointer
arithmetic to copy over byte per byte.

Try it again, but pass the array ByVal.


Mattias