メモとして残しておく

gistfile1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace reverse_polish
{

    public partial class Form1 : Form
    {
        Dictionary<string, int> vals = new Dictionary<string, int>();
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            label1.Text = "" + ExecutePolish(GetPolishString(textBox1.Text));
            return;
        }

        /// <summary>
        /// 数式を逆ポーランド記法に変換します。
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        private string GetPolishString(string s)
        {
            string ret = "";
            var stack = new Stack<char>();
            foreach (var i in s)
            {
                if (i == '+' || i == '-' || i == '*' || i == '/' || i == '=')
                {
                    ret += ",";
                    stack.Push(i);
                }
                else
                    ret += i;

            }
            for (int i = stack.Count() - 1; i >= 0; i--)
            {
                ret += ",";
                ret += stack.Pop();
            }
            return ret;
        }

        private int ExecutePolish(string s)
        {
            var stack = new Stack<string>();
            string n1, n2;

            foreach(var i in s.Split(new char[]{','}))
            {
                if (i[0] >= '0' && i[0] <= '9')
                {
                    stack.Push("" + i);
                }
                else if (i == "+" || i == "-" || i == "*" || i == "/" || i == "=")
                {
                    int r = 0;
                    n2 = stack.Pop();
                    n1 = stack.Pop();
                    switch (i)
                    {
                        case "+":
                            r = int.Parse(n1) + int.Parse(n2);
                            break;
                        case "-":
                            r = int.Parse(n1) - int.Parse(n2);
                            break;
                        case "*":
                            r = int.Parse(n1) * int.Parse(n2);
                            break;
                        case "/":
                            r = int.Parse(n1) / int.Parse(n2);
                            break;
                    }
                    stack.Push("" + r);
                }
                else{
                    stack.Push("" + vals[i]);
                }
            }
            return int.Parse(stack.Pop());
        }

        private void button2_Click(object sender, EventArgs e)
        {
            vals[textBox2.Text] = int.Parse(textBox3.Text);
            listBox1.Items.Add("変数セット：" + textBox2.Text + "=" + textBox3.Text);
        }

        private void button3_Click(object sender, EventArgs e)
        {
            listBox1.Items.Add("変数内容：" + textBox2.Text + "=" + vals[textBox2.Text]);
        }
    }
}