C#窗体-简单计算器

/*1．编写一个计算器，练习在窗体上添加控件、调整控件的布局，设置或修改控件属性， 编写事件处理程序的方法。*/
代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace _20153236_于博_sy3_1
{
    public partial class 计算器 : Form
    {
        double a = 0;
        double b = 0;
        bool c = false;//判断文本框中是否有值
        string d;
        public 计算器()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
        private void button7_Click(object sender, EventArgs e)
        {
            if (c == true)         //有值的话置为空
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "2";
        }
        private void button2_Click_1(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "7";
        }
        private void button5_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "8";
        }
        private void button9_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "9";
        }
        private void button1_Click_1(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "4";
        }
        private void button16_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "1";

        }
        private void button11_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "3";
        }
        private void button6_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "5";
        }
        private void button10_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            } textBox1.Text += "6";
        }
        private void button3_Click(object sender, EventArgs e)
        {
            if (c == true)
            {
                textBox1.Text = "";
                c = false;
            }
            textBox1.Text += "0";
            if (d == "/")
            {
                textBox1.Clear();
                MessageBox.Show("除数不能为零", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }
        private void button8_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true; b = double.Parse(textBox1.Text);
                d = "+";
            }
        }
        private void button15_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true; b = double.Parse(textBox1.Text);
                d = "-";
            }
        }
        private void button14_Click(object sender, EventArgs e)
        {
            if (textBox1.Text=="") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true; b = double.Parse(textBox1.Text);
                d = "*";
            }
        }
        private void button13_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true; b = double.Parse(textBox1.Text);
                d = "/";
            }
        }
        private void button12_Click(object sender, EventArgs e)
        {
             switch (d)
            {
                case "+": a = b + double.Parse(textBox1.Text); break;
                case "-": a = b - double.Parse(textBox1.Text); break;          
                case "*": a = b * double.Parse(textBox1.Text); break;
                case "/": a = b / double.Parse(textBox1.Text); break;
                case "x^2": a = b*b; break;
                case "sqrt": a = Math.Sqrt(b); break;
                case "log": a = Math.Log10(b); break;
                case "ln": a = Math.Log(b); break;
            }       textBox1.Text = a + "";
                c = true;
        }
        private void button4_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
        }
        private void button18_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true;
                b = double.Parse(textBox1.Text);
                d = "x^2";
            }
        }
        private void button19_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true;
                b = double.Parse(textBox1.Text);
                d = "sqrt";
            }
        }
        private void button20_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true;
                b = double.Parse(textBox1.Text);
                d = "log";
            }
        }
        private void button17_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "") { MessageBox.Show("请先输入值再计算！", "错误提示", MessageBoxButtons.OK, MessageBoxIcon.Warning); }
            else
            {
                c = true;
                b = double.Parse(textBox1.Text);
                d = "ln";
            }
        }
    }

}

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