一个简单的C#计算器参考实例 具有四则运算、平方根、百分百、倒数、退位键等基本功能
其界面还调用了Cskin皮肤类库 Ps：CSkin界面库 最强C# NET免费界面库

仅供新手入门参考，知识点涉及到substring、if、按钮事件等

代码地址：码云gitee
部分代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using CCWin;

namespace WindowsFormsApp5 
{
    public partial class Form1 : Skin_Mac
    {
        string strSymbol = "";   //运算符
        string strResult = "";
        double douX=0, douY=0;  //两个操作数
        Button btnBtn;      //按钮类型变量
        public Form1()
        {
            InitializeComponent();
        }
        private void BtnScience_Click(object sender, EventArgs e)
        {
            btnBtn = (Button)sender;
            if (skinTextBox1.Text != "" && skinTextBox2.Text != "")
            {
                switch (btnBtn.Text)
                {
                    case "%":
                        skinTextBox2.Text = skinTextBox1.Text + "%";
                        skinTextBox1.Text = (Convert.ToDouble(skinTextBox1.Text) / 100).ToString();
                        break;
                    case "√":
                        skinTextBox2.Text = "√" + skinTextBox1.Text;
                        skinTextBox1.Text = (Math.Sqrt(Convert.ToDouble(skinTextBox1.Text))).ToString();
                        break;
                    case "X²":
                        skinTextBox2.Text = skinTextBox1.Text+ "²";
                        skinTextBox1.Text = (Math.Pow(Convert.ToDouble(skinTextBox1.Text), 2)).ToString();
                        break;
                    case "1/x":
                        skinTextBox2.Text = "1/" + skinTextBox1.Text;
                        skinTextBox1.Text = (1 / Convert.ToDouble(skinTextBox1.Text)).ToString();
                        break;
                }
                strResult = skinTextBox1.Text;
            }
        }