用ASP.NET做简易计算器和九九乘法表

简易计算器
 
 
1.在页面上放入TextBox控件和dropdownlist控件以及Button控件,形成下图的外观.
 
 
 
 
 
 
 
2.在做好页面后双击Button控件(即"="),写入如下代码:
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
 
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
 
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        double a = Convert.ToDouble(TextBox1.Text);//定义一个变量a，把TextBox1中的值赋给它
        double b = Convert.ToDouble(TextBox2.Text);//定义一个变量b，把TextBox2中的值赋给它
        /*定义的变量为浮点型*/
        if(DropDownList1.SelectedValue == "+" )//获取选择的运算符，确定运算类型
        {
            TextBox3.Text = Convert.ToString(a + b);
        }
        else if (DropDownList1.SelectedValue == "-")
        {
            TextBox3.Text = Convert.ToString(a - b);
        }
        else if (DropDownList1.SelectedValue == "*")
        {
            TextBox3.Text = Convert.ToString(a * b);
        }
        else if (DropDownList1.SelectedValue == "/")
 &nbs