C# 计算器

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;
using System.Text.Regularexpressions;

namespace Calculator
{
    public partial class MainForm : Form
    {
        bool isOver = false; //标记一次运算是否结束，true为结束，false为没结束
        bool isMinus = false; //判断一个数是否为负数，true为负，false为正
        string s1 = null;
        Stack optr = new Stack（）;  //运算符栈
        Stack opnd = new Stack（）;  //运算数栈
        public MainForm（）
        {
            InitializeComponent（）;
            txtFormula.Focus（）;
            optr.Push（“=“）;
        }

        /*private void txtFormula_KeyPress（objec

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2016-06-18 00:27  Calculator\
     目录           0  2016-05-07 16:56  Calculator\.vs\
     目录           0  2016-05-07 16:56  Calculator\.vs\Calculator\
     目录           0  2016-05-07 16:56  Calculator\.vs\Calculator\v14\
     文件        3584  2016-05-07 16:56  Calculator\.vs\Calculator\v14\.suo
     文件         189  2016-04-30 10:23  Calculator\App.config
     文件        3974  2016-05-02 13:01  Calculator\Calculator.csproj
     文件         997  2016-05-09 21:23  Calculator\Calculator.sln
     文件          60  2016-05-02 12:36  Calculator\ClassDiagram1.cd
     文件       28269  2016-05-11 11:30  Calculator\MainForm.Designer.cs
     文件       16022  2016-05-11 11:30  Calculator\MainForm.cs
     文件       20617  2016-05-11 11:30  Calculator\MainForm.resx
     文件         525  2016-04-30 10:55  Calculator\Program.cs
     目录           0  2016-04-30 10:23  Calculator\Properties\
     文件        1328  2016-04-30 10:23  Calculator\Properties\AssemblyInfo.cs
     文件        2833  2016-04-30 10:23  Calculator\Properties\Resources.Designer.cs
     文件        5612  2016-04-30 10:23  Calculator\Properties\Resources.resx
     文件        1097  2016-04-30 10:23  Calculator\Properties\Settings.Designer.cs
     文件         249  2016-04-30 10:23  Calculator\Properties\Settings.settings
     目录           0  2016-04-30 10:23  Calculator\bin\
     目录           0  2016-05-07 17:28  Calculator\bin\Debug\
     文件       31232  2016-05-11 11:30  Calculator\bin\Debug\Calculator.exe
     文件         189  2016-04-30 10:23  Calculator\bin\Debug\Calculator.exe.config
     文件       30208  2016-05-11 11:30  Calculator\bin\Debug\Calculator.pdb
     文件       22696  2016-05-11 11:30  Calculator\bin\Debug\Calculator.vshost.exe
     文件         189  2016-04-30 10:23  Calculator\bin\Debug\Calculator.vshost.exe.config
     文件         490  2015-10-30 15:19  Calculator\bin\Debug\Calculator.vshost.exe.manifest
     目录           0  2016-07-22 22:29  Calculator\bin\Release\
     目录           0  2016-04-30 10:23  Calculator\obj\
     目录           0  2016-05-11 11:30  Calculator\obj\Debug\
     文件       10228  2016-05-11 11:30  Calculator\obj\Debug\Calculator.MainForm.resources
............此处省略13个文件信息