C#实现简单计算器功能

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 cal
{
  public partial class form1 : form
  {
    public double num1;
    public int temp = 0;//记录存储计算方式
    public form1()
    {
      initializecomponent();
    }
    
    private void eq_click(object sender, eventargs e)
    {
      switch (temp)
      {
        //加法运算
        case 1:
          try
          {
            result.text = (num1 + double.parse(result.text)).tostring();
          }
          catch (exception)
          {
            messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
          }
          finally
          {
            temp = 0;
          }
          break;
        //减法运算
        case 2:
          try
          {
            result.text = (num1 - double.parse(result.text)).tostring();
          }
          catch (exception)
          {
            messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
          }
          finally
          {
            temp = 0;
          }
          break;
        //乘法运算
        case 3:
          try
          {
            result.text = (num1 * double.parse(result.text)).tostring();
          }
          catch (exception)
          {
            messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
          }
          finally
          {
            temp = 0;
          }
          break;
        //除法运算，讨论分母为零的情况
        case 4:
          if (double.parse(result.text)==0)
          {
            messagebox.show("除数不能为零", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
            result.resettext();
          }
          else
          {
            result.text = (num1 / double.parse(result.text)).tostring(); temp = 0;
          }
          break;
        case 5:
          try
          {
            result.text = (num1 % double.parse(result.text)).tostring();
          }
          catch (exception)
          {
            messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
          }
          finally
          {
            temp = 0;
          }
          break;
      }
    }

    private void empty_click(object sender, eventargs e)
    {
      result.text = "0";
      num1 = 0;
      temp = 0;
      //清除
      //if (result.text.length > 0)
      //{
      //  result.text = result.text.substring(0, result.text.length - 1);
      //}
    }

    private void zero_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "0";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "0";
      }
    }

    private void one_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "1";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "1";
      }
    }

    private void two_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "2";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "2";
      }
    }
    private void three_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "3";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "3";
      }
    }

    private void four_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "4";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "4";
      }
    }

    private void five_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "5";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "5";
      }
    }

    private void six_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "6";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "6";
      }
    }

    private void seven_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "7";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "7";
      }
    }

    private void eight_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "8";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "8";
      }
    }

    private void nine_click(object sender, eventargs e)
    {
      if (result.text == "0")
      {
        result.text = "9";
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + "9";
      }
    }

    private void point_click(object sender, eventargs e)
    {
      //小数点按键，初始为空，直接按 . 键则显示为0.多少
      if (result.text == "")
      {
        result.text = "0.";
      }
      //如果再次输入.则返回都输入的字符后边并提示信息
      else if (result.text.indexof(".") >= 0)
      {
        messagebox.show("已经输入小数点,无须再次输入", "提示");
      }
      else
      {
        //前边有数字时，则直接在后边加上.
        result.text = result.text + ".";
      }
    }

    private void add_click(object sender, eventargs e)
    {
      temp = 1;
      try
      {
        num1 = double.parse(result.text);
      }
      catch (exception)
      {
        messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
      }
      finally
      {
        result.text = "";//随后让文本框归空
      }
    }

    private void mul_click(object sender, eventargs e)
    {
      temp = 3;
      try
      {
        num1 = double.parse(result.text);
      }
      catch (exception)
      {
        messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
      }
      finally
      {
        result.text = "";//随后让文本框归空
      }
    }

    private void sub_click(object sender, eventargs e)
    {
      temp = 2;
      try
      {
        num1 = double.parse(result.text);
      }
      catch(exception)
      {
        messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
      }
      finally
      { 
      result.text = "";//随后让文本框归空
      }
    }

    private void button1_click(object sender, eventargs e)
    {
      temp = 4;
      try
      {
        num1 = double.parse(result.text);
      }
      catch (exception)
      {
        messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
      }
      finally
      {
        result.text = "";//随后让文本框归空
      }
    }

    private void per_click(object sender, eventargs e)
    {
      temp = 5;
      try
      {
        num1 = double.parse(result.text);
      }
      catch (exception)
      {
        messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
      }
      finally
      {
        result.text = "";//随后让文本框归空
      }
    }

    private void opp_click(object sender, eventargs e)
    {
      //temp = 6;
      try
        {
         result.text = (-double.parse(result.text)).tostring();
        }
      catch (exception)
        {
          messagebox.show("还没输入数字呢", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
        }
      finally
          {
        temp = 0;
          }
    }
    
    private void form1_load(object sender, eventargs e)
    {
      result.text = "0";
    }

    private void result_textchanged(object sender, eventargs e)
    {
      if (result.text.length > 18&& result.text.length<36)
      {
        result.font = new font(result.font.fontfamily, 15, result.font.style);
      }
      if (result.text.length > 36&&result.text.length<45)
      {
        result.font = new font(result.font.fontfamily, 10, result.font.style);
      }
      if (result.text.length > 45)
      {
        messagebox.show("超出范围，将要清空了！", "错误提示", messageboxbuttons.ok, messageboxicon.warning);
        result.resettext();
        result.font = new font(result.font.fontfamily, 20, result.font.style);
      }
    }
  }
}