C#- 设计一个简单的计算器，使其可以加减乘除计算

C#- 设计一个简单的计算器，使其可以加减乘除计算

实现效果图：

如果输入有误，会报错。

代码如下：`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 WindowsFormsApp1
{
public partial class Form1 : Form
{
int flag = 0;
public Form1()
{
InitializeComponent();
}

private void radioButton1_CheckedChanged(object sender, EventArgs e){flag = 1;}private void radioButton2_CheckedChanged(object sender, EventArgs e){flag = 2;}private void radioButton3_CheckedChanged(object sender, EventArgs e){flag =3;}private void radioButton4_CheckedChanged(object sender, EventArgs e){flag =4;}private void add(){double n1 = Convert.ToDouble(textBox1.Text);double n2 = Convert.ToDouble(textBox2.Text);textBox3.Text = Convert.ToString(n1 + n2);}private void sub(){double n1 = Convert.ToDouble(textBox1.Text);double n2 = Convert.ToDouble(textBox2.Text);textBox3.Text = Convert.ToString(n1-n2);}private void mult(){double n1 = Convert.ToDouble(textBox1.Text);double n2 = Convert.ToDouble(textBox2.Text);textBox3.Text = Convert.ToString(n1*n2);}private void div(){double n1 = Convert.ToDouble(textBox1.Text);double n2 = Convert.ToDouble(textBox2.Text);textBox3.Text = Convert.ToString(n1/n2);}private void button1_Click(object sender, EventArgs e){if (textBox1.Text == \"\" || textBox2.Text == \"\"||flag==0){MessageBox.Show(\"请检查输入\", \"提示\", MessageBoxButtons.OK);}else{switch (flag){case 1: add(); break;case 2: sub(); break;case 3: mult(); break;case 4: div(); break;default: break;}}}}

}
`

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