C# 计算器程序

 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace JcCalc
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

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

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

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

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

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

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

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

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

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

        private void btn9_Click(object sender, EventArgs e)
        {
            rtbResult.Text += "9";
        }
        //加法
        private void btnAdd_Click(object sender, EventArgs e)
        {
            lbResult.Text = "";
            string s = rtbResult.Text;
            //判断输入框是否为空
            if (s.Length > 0)
            {
                s = s.Substring(s.Length - 1);
                //如果最后一个是运算符，则返回不执行操作；
                if ("+-*/.".Contains(s)) return;
                rtbResult.Text += "+";
            }
            
        }
        //减法
        private void btnSub_Click(object sender, EventArgs e)
        {
            lbResult.Text = "";
            string s = rtbResult.Text;
            //判断输入框是否为空
            if (s.Length > 0)
            {
                s = s.Substring(s.Length - 1);
                //如果最后一个是运算符，则返回不执行操作；
                if ("+-*/.".Contains(s)) return;
                rtbResult.Text += "-";
            }
        }
        //乘法
        private void btnMul_Click(object sender, EventArgs e)
        {
            lbResult.Text = "";
            string s = rtbResult.Text;
            //判断输入框是否为空
            if (s.Length > 0)
            {
                s = s.Substring(s.Length - 1);
                //如果最后一个是运算符，则返回不执行操作；
                if ("+-*/.".Contains(s)) return;
                rtbResult.Text += "*";
            }
        }
        //除法
        private void btnDiv_Click(object sender, EventArgs e)
        {
            lbResult.Text = "";
            string s = rtbResult.Text;
            //判断输入框是否为空
            if (s.Length > 0)
            {
                s = s.Substring(s.Length - 1);
                //如果最后一个是运算符，则返回不执行操作；
                if ("+-*/.".Contains(s)) return;
                rtbResult.Text += "/";
            }
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            rtbResult.Text = "";
            lbResult.Text = "";
        }

        private void btnDel_Click(object sender, EventArgs e)
        {
            string s = rtbResult.Text;
            //如果S长度大于0，则删除最后一位；
            if (s.Length > 0)        s = s.Substring(0, s.Length - 1);
            rtbResult.Text = s;
        }

        private void btnPoint_Click(object sender, EventArgs e)
        {
            string s = rtbResult.Text;
            //判断输入框是否为空
            if (s.Length > 0)
            {
                s = s.Substring(s.Length - 1);
                //如果最后一个是运算符，则返回不执行操作；
                if ("+-*/.".Contains(s)) return;
                rtbResult.Text += ".";
            }
        }

        private void button19_Click(object sender, EventArgs e)
        {
            float dResult = 0;
            string s = rtbResult.Text;
            //判断输入框是否为空
            try { 
                if (s.Length > 0)
                {
                    //如果没有运算符
                    if (!"+-*/.".Contains(s)) lbResult.Text = s;
                    //s += "+0.1-0.1";
                    //执行计算
                    object result = 999999999999999999999999999999999999999999999999999.99;
                     result = new DataTable().Compute(s, "");
                    string s2 = result.ToString();
                    if (s2 == "∞")
                    {
                        MessageBox.Show("除数不能为0");
                        return;
                    }
                    double db = 0.00;
                    Double.TryParse(s2, out db);
                    lbResult.Text = s2.ToString();
                }
            }
            catch (Exception E)
            {
                MessageBox.Show("我是3年级的小屁孩，数字多了我算不出来！\r\n提示："+E.Message);
                    return;
            }


            }

        /// <summary>
        /// 最简单的方式由SQL计算
        /// </summary>
        /// <param name="expression">表达式</param>
        /// <returns></returns>
        public static float CalcBySQL(string expression)
        {
            string SQL = "SELECT " + expression + " AS RESULT_VALUE";
            SqlConnection conn = new SqlConnection("1=1");
            SqlCommand cmd = new SqlCommand(SQL, conn);
            object o = cmd.ExecuteScalar(); //执行SQL.
            return float.Parse(o.ToString());
        }
        private void btnHelp_Click(object sender, EventArgs e)
        {
            MessageBox.Show("谢谢你长得辣么美，还在点击我！", "三克油");
        }
    }
}