If you want to assign all elements of the cell array, start at jcell=0 (as in the example http://www.mathworks.com/matlabcentral/answers/84135-getting-the-contents-from-cells-in-a-cell-array-using-mex).
mxGetCell replies a NULL pointer if the input is not a cell or if the cell element is not initialized. Check this in every case:
cellArray = mxGetCell(cell,jcell);
if (cellArray == NULL) {
... perform an error or an exception
}
You are writing directly into the input array. This is dangerous, because you do not check if this is a shared array. Never modify the inputs in a C-Mex function, if you are not really sure about what you are doing. But here this can lead to bad values in Matlab, but not to a crash.
jcell is an int and dims an mwSize. Are you sure that jcell<dims[0] does, what you expect? The same happens for i, j and nrow, ncol. Better rely on the same integer types.
