MATLAB: Call C++ class from Matlab

cc plus plus

Is it possible to call C++ classes from Matlab? When I use loadlibrary to load a DLL into Matlab, I get the following errors:

Warning: The data type 'error' used by function CLASSNAME does not exist. 
> In loadlibrary at 421
Warning: The function 'CLASSNAME' was not found in the library 
> In loadlibrary at 421

Would creating a MEX file be any different than using loadlibrary?

Best Answer

Only functions which are

extern "C"

can be called from MATLAB. Those routines have no "this", so only static class methods can be directly called. Those routines can create new objects or reference existing objects, but you cannot pass objects in from MATLAB and cannot return objects to MATLAB.

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Use regular output functions. E.g., ( after you assign the value of cresult but before you destroy the mxArray mresult ):

printf( "The result is %g\n", *cresult );

But note that you will need to pause your program at the end in order to see this output on the screen (otherwise the window will close immediately after printing and you will not see it).

SIDE NOTE:

All of this code:

  int const SIZE=1;
  int const SIZE2=1;
  double x[SIZE][SIZE2];
  x[1][1] = 1.0;
  mxArray *A=NULL;
  A=mxCreateDoubleMatrix(SIZE2, SIZE, mxREAL);
  memcpy((void *)mxGetPr(A), (void *)x, sizeof(double)*SIZE*SIZE2);

can be simplified to this:

  mxArray *A=NULL;
  A = mxCreateDoubleScalar(1.0);

Also, you should be getting in the habit of checking your pointers before using them. E.g., A, mresult, and cresult should all be checked to see that they are not NULL before you try to dereference them.

Best Answer

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