Ekran

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WindowsFormsApp1
{
    public static class Ekran
    {
        private static string s;
        private static bool dot = false;
        private static bool o = false;
        private static int d = 0;

        public static int ostdzialanied()
        {
            return d;
        }


        public static string ostdzialanie()
        {
            switch (d)
            {
                case 0:
                    return "";

                case 1:
                    return "+";

                case 2:
                    return "-";

                case 3:
                    return "*";

                case 4:
                    return "/";
                case 5:
                    return "x^2";
                case 6:
                    return "1/x";
                case 7:
                    return "%";
                case 8:
                    return "+/-";
                case 9:
                    return "SQRT";


                default:
                    return "";

            }
        }

        public static void setdzialanie(int i)
        {
            d = i;
        }

        public static void set(double a)
        {
             set(a.ToString());
        }

        public static void set(string a)
        {
            s = a;
        }

        public static void add(double a)
        {
            add(a.ToString());
        }

        public static void add(string a)
        {
            if (a.Equals("."))
            {
                if (!dot && !o)
                {
                    s += "0.";
                    dot = true;
                    o = true;
                }
                else if (!dot && o)
                {
                    s += ".";
                    dot = true;
                }

            }
            else if (a.Equals("0"))
            {
                if (dot)
                {
                    s += "0";
                }
                else
                {
                    if (!o)
                    {
                        s += "0";
                        o = true;
                    }
                }
            }
            else if (a.Equals("00"))
            {
                if(dot)
                {
                    s += "00";
                }
                else if (!o)
                {
                    o = true;
                    s += "0";
                }
            }
            else
            {
                if (!dot && !o)
                    s += a;
                else if (dot)
                    s += a;
                else if (o && !dot)
                    return;
            }


        }

        public static void clr()
        {
            s = null;
            dot = false;
            o = false;
        }

        public static string rets()
        {
            return s;
        }
        public static double retd()
        {
            return Double.Parse(s);
        }
    }
}