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As mex-files do not make the distinction between single and double quoted strings within Octave, there is perhaps less complexity in the use of strings and character matrices in mex-files. An example of their use, that parallels the demo in stringdemo.cc, is given in the file mystring.c, as seen 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 <string.h> #include "mex.h" void mexFunction (int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { mwIndex i, j; mwSize m, n; mxChar *pi, *po; if (nrhs != 1 || ! mxIsChar (prhs[0]) || mxGetNumberOfDimensions (prhs[0]) > 2) mexErrMsgTxt ("expecting char matrix"); m = mxGetM (prhs[0]); n = mxGetN (prhs[0]); pi = mxGetChars (prhs[0]); plhs[0] = mxCreateNumericMatrix (m, n, mxCHAR_CLASS, mxREAL); po = mxGetChars (plhs[0]); for (j = 0; j < n; j++) for (i = 0; i < m; i++) po [j*m + m - 1 - i] = pi [j*m + i]; }
An example of its expected output is
mystring(["First String"; "Second String"]) => s1 = Second String First String
Other functions in the mex interface for handling character strings are
mxCreateString
, mxArrayToString
, and
mxCreateCharMatrixFromStrings
. In a mex-file, a character string
is considered to be a vector rather than a matrix. This is perhaps an
arbitrary distinction as the data in the mxArray for the matrix is
consecutive in any case.