Passing a structure by reference to C++ DLL

[Gtarawneh]

Hi,

Confused where to post this since it has to do with both C++ and VB.

Using C++, I've made a DLL library (ATL Component) which contains a strucutre. I want to expose the structure definition to the VB application as a data type so it can create a variable with this data type, manipulate it, and pass it by reference to functions in the DLL. Question is: How is that possible?

Thanks in advance!

[kleinma]

couldn't you just create a UDT in VB that has the same set of variables as your C structure?? like when you are using windows API and pass a rect UDT to an API function because it needs the rect structure for its return values.

So if your structure is made up of 3 longs and a string, making a UDT of the same parameters should work for passing..

this is just a guess.. I am not a C programmer so I am not sure if it will work

[Gtarawneh]

Yeah, it's fine in theory, yet I lack the technique

Am facing some trouble because whenever I try to make one of the variables passed into the function a UDT, I get some errors with the compile!

Wonder if anyone could help, or post some code?!?!?

[cyborg]

do you get error in vb or c?
show the struct plz, so we can help you translate it to a udt.

[Gtarawneh]

Am getting the error in C++, anyway: the problem is technical as I said before, and I should face no problem translating the structure, here it is anyway:

typedef struct
{
   int Piece[65];
   int AttackPiece[65];
   int BlackKingP;
   int WhiteKingP;
   int MSF1;
   int MSF2;
   int MyRate;
   int ByPassPos;
   int Cast1; //Black Long
   int Cast2; //Black Short
   int Cast3; //White Long
   int Cast4; //White Shor
} ChessBoard;

[CVMichael]

The thing is that I don't know for sure how the C/C++ compiler you have will take the Int ?, as 16 bit or 32 bit, but it is more likely that it is 32 bit...

So, the struct in VB should be like this:

Type ChessBoard
   Piece(65 - 1) As Long
   AttackPiece(65 - 1) As Long
   BlackKingP As Long
   WhiteKingP As Long
   MSF1 As Long
   MSF2 As Long
   MyRate As Long
   ByPassPos As Long
   Cast1 As Long  ' Black Long
   Cast2 As Long  ' Black Short
   Cast3 As Long  ' White Long
   Cast4 As Long  ' White Shor
End Type

[Gtarawneh]

Anyway, I've managed to do some roundabout solution. so I'll consider it resolved for me, Thanks All!