c# Struct check

gistfile1.txt

//Описать структуру Check: https://ru.wikipedia.org/wiki/%D0%9A%D0%B0%D1%81%D1%81%D0%BE%D0%B2%D1%8B%D0%B9_%D1%87%D0%B5%D0%BA
//Предусмотреть функцию добавления информации о товаре (наименование, количество, цена за единицу товара, скидка) в чек, функцию распечатки чека на экране консоли.




using System;
using System.Text.RegularExpressions;
using System.Collections;
using System.Text;
using System.Threading.Tasks;

// IEnumerator - 586
namespace ConsoleApplication1
{
    public struct Product
    {

        public String name { get; private set; }
        public double count { get; private set; }
        public Double price { get; private set; }
        public Double discount { get; private set; }
        public Double sum { get; private set; }
        public Product(String name, double count, Double price, Double discount)
        {
            this.name = name;
            this.count = count;
            this.price = price;
            this.discount = discount;
            sum = (price - price * (discount / 100)) * count;
        }
        public Product(Product pr)
        {
            this.name = pr.name;
            this.count = pr.count;
            this.price = pr.price;
            this.discount = pr.discount;
            sum = (price - price * (discount / 100)) * count;


        }
        public void Print()
        {
            Console.WriteLine("{0}  {1}*{2}={4}; \ndiscount = {3}%", name, count, price, discount, sum);
        }
    }
    public struct Check : IEnumerable
    {
        public Product[] p;
        public Check(Product[] pr)
        {
            p = new Product[pr.Length];
            for (int i = 0; i < pr.Length; i++)
            {
                p[i] = new Product(pr[i]);
            }
        }
        public Check(Product pr)
        {
            p = new Product[1];
            p[1] = pr;

        }
        IEnumerator IEnumerable.GetEnumerator()
        {
            return (IEnumerator)GetEnumerator();
        }

        private IEnumerator GetEnumerator()
        {
            return new ProductEnum(p);
        }

    }
    class ProductEnum : IEnumerator
    {
        public Product[] _p;
        int position = -1;
        public ProductEnum(Product[] list)
        {
            _p = list;
        }

        public object Current
        {
            get
            {
                try
                {
                    return _p[position];
                }
                catch (IndexOutOfRangeException)
                {
                    throw new InvalidOperationException();
                }
            }
        }

        public bool MoveNext()
        {
            position++;
            return (position < _p.Length);
        }

        public void Reset()
        {
            position = -1;
        }
    }


    class Program
    {
        static void Main(string[] args)
        {
            Product[] p = new Product[3];
            p[0] = new Product("баранка", 1, 2, 0);
            p[1] = new Product("печенька", 2, 7.55, 0);
            p[2] = new Product("пепси 0,5л", 1, 12.20, 3);
            Check one = new Check(p);

            PrintCheck(one);

            Product p2 = new Product("малина", 1.138, 37.55, 2);
            Console.WriteLine();
            Console.WriteLine();
            AddProduct(ref one, p2);

            PrintCheck(one);









        }
        static void AddProduct(ref Check ch, Product p)
        {
            Array.Resize(ref ch.p, ch.p.Length + 1);
            ch.p[ch.p.Length - 1] = new Product(p);
        }
        static void PrintCheck(Check check)
        {
            Double sum = 0;
            Console.WriteLine("Check");
            Console.WriteLine("реклама");
            Console.WriteLine("с логотипом");
            foreach (Product p in check)
            {
                p.Print();
                sum += p.sum;
            }
            //for (int i = 0; i < check.p.Length; i++)
            //{
            //    check.p[i].Print();
            //    sum += check.p[i].sum;
            //}
            Console.WriteLine("Total sum {0:0.00}", sum);
        }
    }




}