Rolf <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> znakeeye wrote:
> > Hi!
> >
> > I have made a DLL in C++/MFC. I have to implement a function that can
> > fill a LabView 2D-array with some data. How can that be done?
> >
> > I suppose the function should look something like this:
> > int MyDllFunction(unsigned char **matrix, int width, int height)
> > {
> > for (int r = 0; r < height; r++)
> > {
> > for (int c = 0; c < width; c++)
> > matrix[r][c] = SomeData(r, c);
> > }
> >
> > return 1;
> > }
>
> int MyDllFunction(unsigned char *matrix, int width, int height)
>
> In fact this is what LabVIEW will generate to be passed to the DLL for a
> two dimensional uInt8 array and your function will have to look like this:
>
> int MyDllFunction(unsigned char *matrix, int width, int height)
> {
> for (int r = 0; r < height; r++)
> {
> for (int c = 0; c < width; c++)
> matrix[r * width + c] = SomeData(r, c);
> }
>
> return 1;
> }
>
> Two dimensional arrays in C are a little underspecified. Some see it as
> a single pointer with column * row elements, others as a pointer to an
> array of pointers. LabVIEW chooses for the first!
>
> > Where should the memory of the array be declared? Maybe LabView can
> > allocate the memory itself and pass the function a char-array
> > (together with the width and height) to my function? How does it work?
>
> The memory should always be allocated by the caller, e.g. LabVIEW in
> this case. Just use an Initialize Array function to allocate the 2
> dimensional array before passing it to the Call Library Function.
>
> Rolf K
So basically my function is valid (although I have to switch rows and
columns for a valid result) and all I need is to make a LabView
program that allocates a 2d-array and passes it to this dll function?
Thanks for the information regarding rows and columns.
/Chris
