C#实现的简单整数四则运算计算器功能示例

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;namespace 计算器{  public partial class Form1 : Form  {    public Form1()    {      InitializeComponent();    }    public　string　num;    public int flag;//用于判断输入的操作符    public double num1, num2;    private void num0_button_Click(object sender, EventArgs e)    {      num = num + "0";      num2 = Convert.ToDouble(num);      textBox.Text = num;    }    private void num1_button_Click(object sender, EventArgs e)//重点算法1    {      if (textBox.Text == "0")      {        num = "1";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "1";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num2_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "2";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "2";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num3_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "3";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "3";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num4_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "4";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "4";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num5_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "5";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "5";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num6_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "6";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "6";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num7_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "7";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "7";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num8_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "8";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "8";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void num9_button_Click(object sender, EventArgs e)    {      if (textBox.Text == "0")      {        num = "9";        textBox.Text = Convert.ToString(num);      }      else      {        num = num + "9";        num2 = Convert.ToDouble(num);        textBox.Text = num;      }    }    private void add_button_Click(object sender, EventArgs e)//重点算法2    {      if (textBox.Text.Length > 0)      {        num1 = Convert.ToDouble(textBox .Text);        num = "";        flag = 1;        textBox.Text = "";        textBox.Focus();      }    }    private void dev_button_Click(object sender, EventArgs e)    {      if (textBox.Text.Length > 0)      {        num1 = Convert.ToDouble(textBox.Text);        num = "";        flag = 2;        textBox.Text = "";        textBox.Focus();      }    }    private void mul_button_Click(object sender, EventArgs e)    {      if (textBox.Text.Length > 0)      {        num1 = Convert.ToDouble(textBox.Text);        num = "";        flag = 3;        textBox.Text = "";        textBox.Focus();      }    }    private void chu_button_Click(object sender, EventArgs e)    {      if (textBox.Text.Length > 0)      {        num1 = Convert.ToDouble(textBox.Text);        num = "";        flag = 4;        // textBox.Text = "";        textBox.Focus();      }    }    private void equ_button_Click(object sender, EventArgs e)    {      switch (flag)      {        case 1:          textBox.Text = Convert.ToString(num1+Convert .ToDouble(num));//重点算法3          num2 = Convert.ToDouble(textBox .Text);          break;        case 2:          textBox.Text = Convert.ToString(num1 - Convert.ToDouble(num));          num2 = Convert.ToDouble(textBox.Text);          break;        case 3:          textBox.Text = Convert.ToString(num1 * Convert.ToDouble(num));          num2 = Convert.ToDouble(textBox.Text);          break;        case 4:          textBox.Text = Convert.ToString(num1 / Convert.ToDouble(num));          num2 = Convert.ToDouble(textBox.Text);          break;      }    }    private void re_button_Click(object sender, EventArgs e)    {      num = "";      textBox.Text = "0";    }  }}