c#计算器

代码没有大的问题，但是起初点击控件无反应，原因是事件代码要自己敲，不能直接粘贴。

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 calculator
{
public partial class Form1 : Form
{
public double num1;//定义第一次输入数
public double num2;//定义第二次输入数
public string sign;//定义运算符
public double num3;//定义结果
public bool check = true;//判断是否为第一次输入数
public double ans;//定义一个ans以便实现连续运算
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{

}

private void button7_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;//定义一个新的button并将点击的button属性赋予它
textBox1.Text += b.Text;//将button的text属性与textbox的text属性相加（字符串相加直接连接）
num1 = double.Parse(textBox1.Text);//将textbox的text转为double型并赋值给num1
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button1_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button2_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button3_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button4_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button5_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button6_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button8_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button9_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button10_MouseClick(object sender, MouseEventArgs e)
{
if (check == true)
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num1 = double.Parse(textBox1.Text);
}
else
{
Button b = (Button)sender;
textBox1.Text += b.Text;
num2 = double.Parse(textBox1.Text);
}
}

private void button11_MouseClick(object sender, MouseEventArgs e)//相反数
{
if (check == true)
{
num1 = 0 - num1;
textBox1.Text = num1.ToString();
}
else
{
num2 = 0 - num2;
textBox1.Text = num2.ToString();
}
}

private void button12_MouseClick(object sender, MouseEventArgs e)//等于
{
if (check == true)
{
num3 = num1;
}
else
{
switch (sign)
{
case "+":
num3 = ans + num2;
break;
case "-":
num3 = ans - num2;
break;
case "*":
num3 = ans * num2;
break;
case "/":
num3 = ans / num2;
break;
case "x²":
num3 = Math.Pow(ans, 2);
break;
}
}
textBox1.Text = num3.ToString();
}

private void button13_MouseClick(object sender, MouseEventArgs e)//平方
{
ans = double.Parse(textBox1.Text);
sign = "x²";
textBox1.Text = "";
check = false;
}

private void button14_MouseClick(object sender, MouseEventArgs e)//除法
{
ans = double.Parse(textBox1.Text);
sign = "/";
textBox1.Text = "";
check = false;
}

private void button15_MouseClick(object sender, MouseEventArgs e)//乘法
{
ans = double.Parse(textBox1.Text);
sign = "*";
textBox1.Text = "";
check = false;
}

private void button16_MouseClick(object sender, MouseEventArgs e)//减法
{
ans = double.Parse(textBox1.Text);
sign = "-";
textBox1.Text = "";
check = false;
}

private void button17_MouseClick(object sender, MouseEventArgs e)//CE
{
textBox1.Text = "";
num1 = 0;
num2 = 0;
num3 = 0;
ans = 0;
check = true;
}

private void button18_MouseClick(object sender, MouseEventArgs e)//加法
{
ans = double.Parse(textBox1.Text);
sign = "+";
textBox1.Text = "";
check = false;
}
}
}