Re: passing array from c++ wrapper to c function

[Andy Buckle]

> Now, I am stuck again, because I cannot pass back to C++ a vector from C.

In C you have to worry about allocating and freeing memory. If you
created (allocated memory for) an array within your C function, then
you would have to worry about freeing it. If you use the Octave API to
create your matrix to return, then I think* that Octave takes care of
this for you.

The C way is to be given pointers to pre-allocated arrays, one with
the input, and one for the output. This is how I would do it

*
and would appreciate correction from those more knowledgeable

---------------------------
#include <octave/oct.h>

extern "C"
{
    void t3 (double *p_out, double *p_in, int len)
    {
       for (int i=0; i<len; i++)
       {
           p_out[i]=p_in[i]*2;
       }
    }
}


DEFUN_DLD (t3, args, , "test interpolation")
{
   octave_value_list retval;

   Array<double> ar = args(0).array_value ();
   int len=ar.length();

   // create output arg
   Matrix out(ar.rows(), ar.columns());

   t3(out.fortran_vec(), ar.fortran_vec(), len);

   retval(0) = octave_value(out);

   return retval ;
}
---------------------------
-- 
/* andy buckle */