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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.
#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
There are a couple of additional functions available in mex-files of
interest in the treatment of strings. These are mxCreateString
,
mxArrayToString
and mxCreateCharMatrixFromStrings
. A
string in a mex-file 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 consequetive in any case.