【实验要求】

（1）新建一个C#桌面项目Calc，实现简易计算器功能，界面如图1所示。

（2）计算方式：通过点击对应的按钮，输入第1个数（可以是整数或实数），输入运算符（+、-、*或/），再输入第2个数，点击“=”按钮，完成计算。

（3）（选做）改进程序的设计，要求输入一个算术表达式，点击“=”按钮完成输入表达式的计算并输出（可以利用数据结构中的表达式计算原理，实现表达式的计算）。

【实验步骤】

红色为每个按钮的方法名

【Form1.cs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;

namespace Calc
{
    public partial class frmMain : Form
    {
        private double num1;//左操作数
        private double num2;//右操作数
        private string flag;//flag为当前所操作的运算符
        private double res;//计算结果
        private bool isCalc;//判断是否计算
        public frmMain()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
         
        }

        private void Button1_Click(object sender, EventArgs e)
        {
            //次方运算
            num1 = Convert.ToDouble(txtNum.Text);
            flag = "sqr";
            txtNum.Text = "";
        }

        private void btnC_Click(object sender, EventArgs e)
        {
            //按钮“C”，清空
            txtNum.Text = "";
        }

        private void btnBack_Click(object sender, EventArgs e)
        {
            //回退键
            if(txtNum.Text.Length > 0)
            {
                txtNum.Text = txtNum.Text.Substring(0, txtNum.Text.Length - 1);
            }
        }

        private void btnDiv_Click(object sender, EventArgs e)
        {
            //除法按钮
            num1 = Convert.ToDouble(txtNum.Text);
            flag = "/";
            txtNum.Text = "";
        }

        private void btn7_Click(object sender, EventArgs e)
        {
            txtNum.Text += "7";
        }

        private void btn8_Click(object sender, EventArgs e)
        {
            txtNum.Text += "8";
        }

        private void btn9_Click(object sender, EventArgs e)
        {
            txtNum.Text += "9";
        }

        private void btnMul_Click(object sender, EventArgs e)
        {
            //乘法按钮
            num1 = Convert.ToDouble(txtNum.Text);
            flag = "*";
            txtNum.Text = "";
        }

        private void btn4_Click(object sender, EventArgs e)
        {
            txtNum.Text += "4";
        }

        private void btn5_Click(object sender, EventArgs e)
        {
            txtNum.Text += "5";
        }

        private void btn6_Click(object sender, EventArgs e)
        {
            txtNum.Text += "6";
        }

        private void btnSub_Click(object sender, EventArgs e)
        {
            //减法按钮
            num1 = Convert.ToDouble(txtNum.Text);
            flag = "-";
            txtNum.Text = "";
        }

        private void btn1_Click(object sender, EventArgs e)
        {
            txtNum.Text += "1";
        }

        private void btn2_Click(object sender, EventArgs e)
        {
            txtNum.Text += "2";
        }

        private void btn3_Click(object sender, EventArgs e)
        {
            txtNum.Text += "3";
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            //加法按钮
            num1 = Convert.ToDouble(txtNum.Text);
            flag = "+";
            txtNum.Text = "";
        }

        private void btnOr_Click(object sender, EventArgs e)
        {
            //正负号按钮
            if(txtNum.Text == "0")
            {
                return;
            }
            if (txtNum.Text.Contains("-"))
            {
                txtNum.Text = txtNum.Text.Substring(1);
            }
            else
            {
                txtNum.Text = "-" + txtNum.Text;
            }
        }

        private void btn0_Click(object sender, EventArgs e)
        {
            txtNum.Text += "0";
        }

        private void btnPoint_Click(object sender, EventArgs e)
        {
            txtNum.Text +=  ".";
        }

        private void btnEqual_Click(object sender, EventArgs e)
        {
            int f = 1;
            num2 = Convert.ToDouble(txtNum.Text);
            if(flag == "+")//加法运算
            {
                res = num1 + num2;
            }else if(flag == "-")//减法运算
            {
                res = num1 - num2;
            }else if(flag == "*")//乘法运算
            {
                res = num1 * num2;
            }else if(flag == "/")//除法运算
            {
                if(num2 == 0)
                {
                    txtNum.Text = "除数不能为0";
                    f = 0;
                }
                else
                {
                    res = num1 / num2;
                }
            }
            else 
            {
                //n次方运算
                res = Math.Pow(num1,num2);              
            }
            if(f == 1)
            {
                txtNum.Text = res.ToString();
            }
        }
    }
}

【计算器效果演示】

计算器演示

不知道为什么录屏没给我录到头顶，将就看看。