How to initialize 2D object

Question

I'm trying to figure out how to start a two dimensional array of an object. I have point class and I want to create Rectangle class that build from 2D arrays of points. I want to initialize the public Point[,] StartPoint somting like this = new [,]Point(); What the right way to do it?

{
class Point
{
    public int X { get; set; }
    public int Y { get; set; }

    public Point()
    {
        X = 0;
        Y = 0;
    }
    public Point(int x , int y)
    {
        X = x;
        Y = y;
    }
}
}

Rectangele class :

{
class SRectangle
{
    public Point[,] StartPoint;
    public int Rows ;
    public int Cols ;



    public SRectangle(Point start , int row, int col)
    {
        Rows = row;
        Cols = col;
        for (int i = 0; i <= Rows; i++)
        {
            for (int j = 0; j <= Cols; j++)
            {
                StartPoint[i, j] = new Point(Rows + i, Cols + j);
            }
        }
    }
}

}

Answer 1

You don't need a multidimensional array to keep a store of points, they themselves store x and y. You only need a simple array f points for a rectangle, But I see your concern, what you seem to want is:

but because it is class I can't write something like this 'public Point[,] StartPoint = new Point,;

You want to access points using an index as if you were storing X and Y combinations. But You aren't, you're storing an array of objects which have information about X and Y's however there is a way to get the point by (x,y)index

1. Insist on using a 2d array, in which Points[x,y] will have an object with the same X and Y ie you might as well have stored int[,] and it wouldn't have mattered.

2. Treat the array as a 2d but really having a 1d array.

//my rectangle class
class Rectangle
{
    public Point[,] Points;
    public int Rows ;
    public int Cols ;



    public Rectangle(Point start, int row, int col)
    {
        Rows = row;
        Cols = col;
        Points = new Point[Rows, Cols];
        for (int i = 0; i <= Rows; i++)
        {
            for (int j = 0; j <= Cols; j++)
            {
                Points[i, j] = new Point(Rows + i, Cols + j);
            }
        }
        //now use it like Points[x, y]
    }
}

//my rectangle class
class Rectangle
{
    public Point[] Points;
    public int Rows;
    public int Cols;

    public Rectangle(Point start, int row, int col)
    {
        Rows = row;
        Cols = col;
        Points = new Point[Rows * Cols];
        for (int i = 0; i <= Rows; i++)
        {
            for (int j = 0; j <= Cols; j++)
            {
                Points[(i * Cols) + j] = new Point(Rows + i, Cols + j);
            }
        }
    }
        
    //return the point if it exists else null
    public Point? GetPoint(int x, int y)
    {
       int index = (i * Cols) + j;
       if (index < Points.Length)
           return Points[index];
       return null;
    }
}