c++ dll takes unsigned char* as paramater and fills it out, how to use in MATLAB

I have a function

int Read(int cindx, unsigned char* buffer, int readamount) in a dll

it fills the buffer out with new data, how do I get this data in Matlab

I have been looking all over and seems I can't find it

(looked at libpointer, and char) can't make sense of it)

I have a C++ background

using MATLAB 7.10.0 32bit

Answer 1

[Kaustubha Govind]

I'm not very familiar with this, but a similar question has been answered here: http://www.mathworks.com/matlabcentral/answers/6198-attempt-to-call-external-dll-function-causing-segmentation-fault

So it seems that you should pre-allocate a char buffer as suggested in that answer:

   b = char(zeros(1,1024))

and pass this in place of the char* buffer parameter.

Btw, I don't know how well C++ DLLs work with LOADLIBRARY. As far as I know, LOADLIBRARY uses the LCC compiler to parse the symbols in the DLL to be loaded. Since LCC is a C compiler, it does not handle C++ syntax well. However, judging from your function signature, it looks very C-style, so you might be able to get away with it.

[Kaustubha Govind]

Update: While answering another question (here: http://www.mathworks.com/matlabcentral/answers/20702-loadlibrary-calls-lcc-by-default), I found that starting in R2011a, LOADLIBRARY picks up the compiler selected using "mex -setup". So you should be able to load C++ DLLs my selecting a C++ compiler.