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We can perform exactly the same operations in Cell arrays in mex-files as we can in oct-files. An example that reduplicates the functional of the celldemo.cc oct-file in a mex-file is given by mycell.c as below
/* Copyright (C) 2006, 2007 John W. Eaton This file is part of Octave. Octave is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. Octave is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Octave; see the file COPYING. If not, see <http://www.gnu.org/licenses/>. */ #include "mex.h" void mexFunction (int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) { mwSize n; mwIndex i; if (nrhs != 1 || ! mxIsCell (prhs[0])) mexErrMsgTxt ("expects cell"); n = mxGetNumberOfElements (prhs[0]); n = (n > nlhs ? nlhs : n); for (i = 0; i < n; i++) plhs[i] = mxDuplicateArray (mxGetCell (prhs[0], i)); }
which as can be seen below has exactly the same behavior as the oct-file version.
[b1, b2, b3] = mycell ({1, [1, 2], "test"}) => b1 = 1 b2 = 1 2 b3 = test
Note in the example the use of the mxDuplicateArry
function. This
is needed as the mxArray
pointer returned by mxGetCell
might be deallocated. The inverse function to mxGetCell
is
mcSetCell
and is defined as
void mxSetCell (mxArray *ptr, int idx, mxArray *val);
Finally, to create a cell array or matrix, the appropriate functions are
mxArray *mxCreateCellArray (int ndims, const int *dims); mxArray *mxCreateCellMatrix (int m, int n);