C#计算器编写代码

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

namespace Calculator
{
  public partial class Form1 : Form
  {
    private List<double> value_list = new List<double>();//存用户输入的数字
    private List<int> operator_list = new List<int>();//存用户输入的运算符，定义+为0，-为1，×为2，÷为3
    //状态记录
    private bool add_flag = false;//+按下
    private bool minus_flag = false;//-按下
    private bool multi_flag = false;//×按下
    private bool div_flag = false;//÷按下
    private bool result_flag = false;//=按下
    private bool can_operate_flag = false;//按下=是否响应

    public Form1()
    {
      InitializeComponent();
    }

    //数字键按下，含0与.，类似000001223这类情况这里允许，因为C#可以讲000001223自己转化为1223
    private void num_down(string num)
    {
      if (add_flag || minus_flag || multi_flag || div_flag || result_flag)
      {
        if (result_flag)//按下等号，刚刚算完一个运算的状态
        {
          label1.Text = "";
        }
        textBox1.Clear();//如果用户刚刚输入完一个运算符
        add_flag = false;
        minus_flag = false;
        multi_flag = false;
        div_flag = false;
        result_flag = false;
      }
      if ((num.Equals(".") && textBox1.Text.IndexOf(".") < 0) || !num.Equals("."))
      {
        //如果用户输入的是小数点.，则要判断当前已输入的数字中是否含有小数点.才允许输入
        textBox1.Text += num;
        label1.Text += num;
        can_operate_flag = true;
      }
    }


    private void bt0_Click(object sender, EventArgs e)
    {
      num_down("0");
    }

    private void bt1_Click(object sender, EventArgs e)
    {
      num_down("1");
    }

    private void bt2_Click(object sender, EventArgs e)
    {
      num_down("2");
    }

    private void bt3_Click(object sender, EventArgs e)
    {
      num_down("3");
    }

    private void bt4_Click(object sender, EventArgs e)
    {
      num_down("4");
    }

    private void bt5_Click(object sender, EventArgs e)
    {
      num_down("5");
    }

    private void bt6_Click(object sender, EventArgs e)
    {
      num_down("6");
    }

    private void bt7_Click(object sender, EventArgs e)
    {
      num_down("7");
    }

    private void bt8_Click(object sender, EventArgs e)
    {
      num_down("8");
    }

    private void bt9_Click(object sender, EventArgs e)
    {
      num_down("9");
    }

    private void bt_point_Click(object sender, EventArgs e)
    {
      num_down(".");

    }

    //符号键的输入
    private void bt_plus_Click(object sender, EventArgs e)
    {
      if (!add_flag)//防止用户多次输入一个符号键，符号键只允许输入一次
      {
        result_flag = false;
        value_list.Add(double.Parse(textBox1.Text));//将当前已输入的数字放入value_list
        operator_list.Add(0);
        label1.Text += "+";
        add_flag = true;
        can_operate_flag = false;//刚刚输入完符号，不能构成一条正常的表达式，如111+，设置为不可运行状态
      }
    }

    private void bt_minus_Click(object sender, EventArgs e)
    {
      if (!minus_flag)
      {
        result_flag = false;
        value_list.Add(double.Parse(textBox1.Text));
        operator_list.Add(1);
        label1.Text += "-";
        minus_flag = true;
        can_operate_flag = false;
      }
    }

    private void bt_multi_Click(object sender, EventArgs e)
    {
      if (!multi_flag)
      {
        result_flag = false;
        value_list.Add(double.Parse(textBox1.Text));
        operator_list.Add(2);
        label1.Text = "(" + label1.Text + ")" + "×";//给前面的已经输入的东西加个括号。（运算符栈问题是一个很复杂的数据结构问题，这里不做，：P）
        multi_flag = true;
        can_operate_flag = false;
      }
    }

    private void bt_div_Click(object sender, EventArgs e)
    {
      if (!div_flag)
      {
        result_flag = false;
        value_list.Add(double.Parse(textBox1.Text));
        operator_list.Add(3);
        label1.Text = "(" + label1.Text + ")" + "÷";
        div_flag = true;
        can_operate_flag = false;
      }
    }

    private void bt_result_Click(object sender, EventArgs e)
    {

      if (value_list.Count > 0 && operator_list.Count > 0 && can_operate_flag)
      {//需要防止用户没输入数字，或者只输入了一个数，就按=。
        value_list.Add(double.Parse(textBox1.Text));
        double total = value_list[0];
        for (int i = 0; i < operator_list.Count; i++)
        {
          int _operator = operator_list[i];//operator是C#的运算符重载的关键字，前面加个_来区别
          switch (_operator)
          {
            case 0:
              total += value_list[i + 1];
              break;
            case 1:
              total -= value_list[i + 1];
              break;
            case 2:
              total *= value_list[i + 1];
              break;
            case 3:
              total /= value_list[i + 1];
              break;
          }
        }
        textBox1.Text = total + "";
        label1.Text = total + "";
        operator_list.Clear();//算完，就清空累积数字与运算数组
        value_list.Clear();
        result_flag = true;//表示=按下
      }
    }

    //CE键，将所有东西初始化
    private void btCE_Click(object sender, EventArgs e)
    {
      operator_list.Clear();
      value_list.Clear();
      add_flag = false;
      minus_flag = false;
      multi_flag = false;
      div_flag = false;
      result_flag = false;
      can_operate_flag = false;
      textBox1.Clear();
      label1.Text = "";
    }

  }
}