Question

What’s the best data structure for a 2D array of size unknown x 2. Which means one dimension is dynamic (list of grocery items) and the other is fixed (price and quantity).

Answer 1

Personally, I would use a List<T>, with T being a custom class.

This would be something like:

public class GroceryItem { 
   public string Name { get; set; }
   // ...
}
public class PurchaseLineItem
{
    public double Price { get; set; }
    public int Quantity { get; set; }
    public GroceryItem Item { get; set; }
    // ...
}

Then just do:

List<PurchaseLineItem> items = new List<PurchaseLineItem>();

This gives you the flexibility to have your price and quanities, for any number of items. It’s easy to add to this as needed, and make it as long as you want.