winform制作简单计算器

 public Form1()
         {
             InitializeComponent();
             textBox2.Text = "";//主显示屏
             textBox1.Text = "";//顶端副显示屏
             textBox3.Text = "";//中间变量，隐藏

         }

         private void Form1_Load(object sender, EventArgs e)
         {

         }
         //数字按键
         private void button21_Click(object sender, EventArgs e)
         {
             if (sender is Button)
             {
                 Button btn = sender as Button;
                 if (textBox2.Text == "")//如果主屏幕为0
                 {
                     textBox2.Text = btn.Text;//输入几就显示几
                 }
                 else
                 {
                     if (yunsuanfu)//上个按键是运算符
                     {
                         textBox2.Text = btn.Text;//主屏幕只显示本次输入的数字
                         yunsuanfu = false;
                     }
                     else
                     {
                         textBox2.Text += btn.Text;//上个按键不是运算符，主屏幕右侧累添上这个数字
                     }
                 }
             }
         }

         //加减乘除
         private bool yunsuanfu = false;
         private double jieguo1 = ;//点击加减乘除运算符显示的结果
         private string text = "";
         private void button26_Click(object sender, EventArgs e)
         {
             if (sender is Button)
             {
                 Button btn = sender as Button;
                 text = btn.Text;
                 if(textBox3.Text=="")
                 {
                     textBox3.Text = btn.Text;
                 }
                 //判断上一步点击的是否是运算符
                 if (yunsuanfu==false)//不是运算符
                 {
                     textBox1.Text += textBox2.Text + text;
                     yunsuanfu = true;
                     if(textBox3.Text=="+")
                     {
                         jieguo1 += Convert.ToDouble(textBox2.Text);
                         textBox2.Text = jieguo1.ToString();
                     }
                     else if (textBox3.Text == "-")
                     {
                         jieguo1 -= Convert.ToDouble(textBox2.Text);
                         textBox2.Text = jieguo1.ToString();
                     }
                     else if (textBox3.Text == "*")
                     {
                         if (jieguo1 != )
                         {
                             jieguo1 = jieguo1 * Convert.ToDouble(textBox2.Text);
                         }
                         else
                         {
                             jieguo1 = Convert.ToDouble(textBox2.Text);
                         }
                         textBox2.Text = jieguo1.ToString();
                     }
                     else if (textBox3.Text == "/")
                     {
                         if (Convert.ToDouble(textBox2.Text) != )
                         {
                             if (jieguo1 != )
                             {
                                 jieguo1 = jieguo1 / Convert.ToDouble(textBox2.Text);
                             }
                             else
                             {
                                 jieguo1 = Convert.ToDouble(textBox2.Text); ;
                             }
                             textBox2.Text = jieguo1.ToString();
                         }
                         else
                         {
                             textBox2.Text = "除数不能为0";
                         }
                     }

                     textBox3.Text = text;
                 }
                 else
                 {
                     if (textBox1.Text.Length > )
                     {
                         textBox1.Text = textBox1.Text.Substring(, textBox1.Text.Length - ) + text;
                         textBox3.Text = text;
                     }
                     else
                     {
                         textBox3.Text = text;
                     }
                     yunsuanfu = false;
                 }
             }
         }

         //小数点
         private void button25_Click(object sender, EventArgs e)
         {
             //判断上一步点击的是否是运算符
             if (yunsuanfu == false)//不是运算符
             {
                 if (textBox2.Text.Contains(".") == false)
                 {
                     textBox2.Text = textBox2.Text + ".";
                 }
             }
             else
             {
                 textBox2.Text = "0.";
                 yunsuanfu = false;
             }
         }

         //等号
         private double jieguo = ;
         private string text4 = "";
         private string text5 = "";
         private void button28_Click(object sender, EventArgs e)
         {
             jieguo = jieguo1;
             jieguo1 = ;
             text4 = textBox3.Text;
             textBox3.Text = "";
             text = "";
             if (text4 == "")
             {
                 text4 = button28.Text;
             }

             textBox1.Clear();
             textBox1.Text = "";
             //判断上一步点击的是否是运算符
             if (yunsuanfu == false)//不是运算符
             {
                 yunsuanfu = true;
                 if (text4 == "+")
                 {
                     jieguo += Convert.ToDouble(textBox2.Text);
                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "-")
                 {
                     jieguo -= Convert.ToDouble(textBox2.Text);
                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "*")
                 {
                     if (jieguo != )
                     {
                         jieguo = jieguo * Convert.ToDouble(textBox2.Text);
                     }
                     else
                     {
                         jieguo = Convert.ToDouble(textBox2.Text);
                     }
                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "/")
                 {
                     if (textBox2.Text != "")
                     {
                         if (jieguo != )
                         {
                             jieguo = jieguo / Convert.ToDouble(textBox2.Text);
                         }
                         else
                         {
                             jieguo = Convert.ToDouble(textBox2.Text); ;
                         }
                         textBox2.Text = jieguo.ToString();
                     }
                     else
                     {
                         textBox2.Text = "除数不能为0";
                     }
                 }
                 else if (text4 == "=")
                 {
                     jieguo = jieguo;
                 }

                 text5 = text4;
                 text4 = button28.Text;
             }
             else
             {
                 yunsuanfu = false;
                 double jishu = ;
                 if (text4 == "+")
                 {
                     jishu = jieguo;
                     jieguo += jishu;

                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "-")
                 {
                     jishu = jieguo;
                     jieguo -=jishu;

                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "*")
                 {
                     jishu = jieguo;
                     jieguo=jieguo*jishu;

                     textBox2.Text = jieguo.ToString();
                 }
                 else if (text4 == "/")
                 {
                     if (jieguo != )
                     {
                         jishu = jieguo;
                         jieguo = jieguo / jishu;

                         textBox2.Text = jieguo.ToString();
                     }
                     else
                     {
                         textBox2.Text = "除数不能为0";
                     }
                 }
                 else if (text4 == "=")
                 {
                     jishu =Convert.ToDouble(textBox1.Text);
                     if (text5 == "+")
                     {
                         jieguo+=jishu ;
                     }
                     else if (text5 == "-")
                     {
                         jieguo-=jishu;
                     }
                     else if (text5 == "*")
                     {
                         jieguo *=jishu;
                     }
                     else if (text5 == "/")
                     {
                         if (jishu != )
                         {
                             jieguo /= jishu;
                         }
                         else
                         {
                             textBox2.Text = "除数不能为0";
                         }
                     }
                 }
             }
             yunsuanfu = false;

         }
         //按键C
         private void button8_Click(object sender, EventArgs e)
         {
             textBox2.Clear();
             textBox1.Clear();
             textBox3.Clear();
             textBox2.Text = "";
             textBox1.Text = "";
             textBox3.Text = "";
             jieguo = ;
             jieguo1 = ;
             yunsuanfu = false;
             text = "";
             text4 = "";
             text5 = "";
         }
         //CE键
         private void button7_Click(object sender, EventArgs e)
         {

             textBox2.Clear();
             textBox2.Text = "";
         }
         //退格键
         private void button6_Click(object sender, EventArgs e)
         {
             if (textBox2.Text.Length > )
             {
                 textBox2.Text = textBox2.Text.Substring(, textBox2.Text.Length - );
             }
             else if (textBox2.Text.Length == )
             {
                 textBox2.Text = textBox2.Text.Substring(, textBox2.Text.Length - );
                 textBox2.Text = "";
             }
             else
             {
                 textBox2.Text = "";
             }
         }
         //主屏幕字体随个数变化而变化
         private void textBox2_TextChanged(object sender, EventArgs e)
         {
             if (textBox2.Text.Length < )
             {
                 this.textBox2.Font = new System.Drawing.Font("宋体", 21.75f);
             }
             if (textBox2.Text.Length > )
             {
                 this.textBox2.Font = new System.Drawing.Font("宋体", 15f);
             }
             if (textBox2.Text.Length > )
             {
                 this.textBox2.Font = new System.Drawing.Font("宋体", 13f);
             }
             if (textBox2.Text.Length > )
             {
                 this.textBox2.Font = new System.Drawing.Font("宋体", 11f);
             }
         }