Store std::strings in mex cell array - matlab

Question

Inspired from this post, I am interested to pass std::strings into the cell array. However, the mxDuplicateArray accepts mxArray format variables. I have tried to transform the std::string to mxArray with mxGetString but without success.
Could you please make a suggestion on this?
Thanks!
void mexFunction(int nlhs, mxArray *plhs[],int nrhs, const mxArray *prhs[])
{
std::string str ("Hellooo");
const char *cstr = str.c_str();
mwSize len = 10;
mxArray *mxarr = mxCreateCellMatrix(len, 1);
mxArray *mxstr = mxCreateString("");
mxGetString(mxstr, (char*) cstr, str.length());
for(mwIndex i=0; i<len; i++) {
// I simply replaced the call to mxDuplicateArray here
mxSetCell(mxarr, i, mxDuplicateArray(mxstr));
}
mxDestroyArray(mxstr);
plhs[0] = mxarr;
}

Answer 1

You could also cut out the call to mxDuplicateArray (and mxDestroyArray).
#include "mex.h"
#include <string>
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
std::string str("Hellooo");
const char *cstr = str.c_str();
mwSize len = 10;
mxArray *mxarr = mxCreateCellMatrix(len, 1);
for (mwIndex i=0; i<len; i++) {
mxSetCell(mxarr, i, mxCreateString(cstr));
}
plhs[0] = mxarr;
}
Untested...

Answer 2

From the docs on mxGetString:
Call mxGetString to copy the character data of a string mxArray
What you want, is the opposite: create an mxArray from a c-style string. For that you can use
mxCreateString directly. It seems to tried to use it to create an empty string at first. This should work:
void mexFunction(int nlhs, mxArray *plhs[],int nrhs, const mxArray *prhs[])
{
std::string str ("Hellooo");
const char *cstr = str.c_str();
mwSize len = 10;
mxArray *mxarr = mxCreateCellMatrix(len, 1);
mxArray *mxstr = mxCreateString(cstr);
// no need for this line
// mxGetString(mxstr, (char*) cstr, str.length());
for(mwIndex i=0; i<len; i++) {
// I simply replaced the call to mxDuplicateArray here
mxSetCell(mxarr, i, mxDuplicateArray(mxstr));
}
mxDestroyArray(mxstr);
plhs[0] = mxarr;
}