Next: Cell Arrays with Mex-Files, Previous: Working with Matrices and Arrays in Mex-Files, Up: Mex-Files [Contents][Index]
As mex-files do not make the distinction between single and double quoted strings that Octave does, there is perhaps less complexity in the use of strings and character matrices. An example of their use that parallels the demo in stringdemo.cc is given in the file mystring.c, as shown below.
#include <string.h> #include "mex.h" void mexFunction (int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { mwSize m, n; mwIndex i, j; mxChar *pi, *po; if (nrhs != 1 || ! mxIsChar (prhs[0]) || mxGetNumberOfDimensions (prhs[0]) > 2) mexErrMsgTxt ("ARG1 must be a 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"]) ⇒ 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.