# C++ newbie qu: grid construction for finite difference

1. Nov 29, 2009

### bzz77

Hello everyone:

I am a C++ newbie; I am interesting in using C++ in my work on coupled fluid flow-chemical reaction problems. I apologize in advance for what is probably a very simple question. I would very much appreciate any help to get me on the right track!

My goal is to come up with C++ code for solving a finite difference problem. To do this, I need to (1) construct a 2-D grid and (2) link a struct of data (fluid properties, like density) to the grid. At some point, as I become more experienced, I'd like to learn how to use pointers and iterators, etc, but for now I would like to keep things as simple as possible.

Using some examples, I have come up with a way of constructing a grid that mostly makes sense. But I cannot figure out how to link the grid with a struct of fluid properties. Sorry--I'm certain this is a simple thing to do. If anyone has any suggestions, I would love to hear them. Once I have this problem sorted out, I have a couple of further questions about the grid construction. Thanks a lot.

Here is my grid:

template <typename T>
class Grid2D
{
public:
Grid() : xsize_(0), ysize_(0), grid_(0) { }
Grid(double xsize, double ysize) : xsize_(xsize), ysize_(ysize), grid_(new T[ xsize_ * ysize_ ]) { }

~Grid() { delete[ ] grid_; }
Create(double xsize, double ysize)
{
xsize_ = xsize;
ysize_ = ysize;
grid_ = new T[ xsize_ * ysize_ ];
}
Resize(double xsize, double ysize)
{
xsize_ = xsize;
ysize_ = ysize;
delete[ ] grid_;
grid_ = new T[ xsize_ * ysize_ ];
}
Delete()
{
xsize_ = 0;
ysize_ = 0;
delete[ ] grid_;
grid_ = 0;
}
double xsize() const { return xsize_; }
double ysize() const { return ysize_; }
T& operator(double x, double y) { return grid_[ y*xsize_ + x ]; }
const T& operator(double x, double y) const { return grid_[ y*xsize_ + x ]; }
private:
double xsize_, ysize_;
T* grid_;
}