overloaded grid/matrix class for large objects

[karlo]

I'm trying to design a class for a 2-dimensional grid:

template< class T> class Grid {
private:
    unsigned int sizeX;
    unsigned int sizeY;
    T* data;    // vector with data of the gridpoints
public:
    Grid(unsigned int nRows, unsigned int nCols){
        data = new T(nRows*nCols);
        sizeY = nRows;
        sizeX = nCols;
    }
    // acces a gridpoint:
    inline T& operator()(unsigned int row, unsigned int col){
        assert(row<=sizeY);
        assert(col<=sizeX);
        return data[row*sizeX + col];
    }
};

This works for Grids with a small number of gridpoints i.e.

int main() {
   Grid<double> grid(20,30);
   grid(3,3)=2;
}

but it fails for some reasons if the dimensions are >500. (exit value 139)
Do you see a reason for this problem?

[jsmith]

data = new T(nRows*nCols)

allocates space for one T object and assigns in the value nRows*nCols.

You wanted

data = new T[ nRows*nCols ];

[karlo]

Oh yes, what a simple mistake. Thank you!