using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Web;

 /// <summary>

 ///Class1 的摘要说明

 /// </summary>

 interface  Iface

 {

     int Calation(int a, int b);

 }

 public class Add:Iface

 {

     public int Calation(int a,int b)

     {

         return a+b;

     }

 }

 public class Sub : Iface

 {

     public int Calation(int a, int b)

     {

         return a - b;

     }

 }

 public class Mul : Iface

 {

     public int Calation(int a, int b)

     {

         return a * b;

     }

 }

 public class Div : Iface

 {

     public int Calation(int a, int b)

     {

         if (b == )

         {

             throw new Exception("除数不能为零！");

         }

         else

         {

             return a / b;

         }

     }

 }

 public class Faction

 {

     private Iface iface;

     public Faction(string operation)

     {

         switch (operation)

         {

             case "+":

                 iface = new Add();

                 break;

             case "-":

                 iface = new Sub();

                 break;

             case "*":

                 iface = new Mul();

                 break;

             case "/":

                 iface = new Div();

                 break;

         }

     }

     public int Calationss(int a, int b)

     {

         return iface.Calation(a, b);

     }

 }

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            ti();

        }

    }

    public void ti()

    {

        Random rd = new Random();

        TextBox1.Text = rd.Next(, ).ToString();

        TextBox2.Text = rd.Next(, ).ToString();

        string[] oper = new string[] { "+", "-", "*", "/" };

        Random rdd = new Random();

        Label1.Text = oper[rdd.Next(, )];

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        Faction faction = new Faction(Label1.Text);

        int a = int.Parse(TextBox1.Text);

        int b = int.Parse(TextBox2.Text);

        string anster = faction.Calationss(a, b).ToString();

        if (TextBox3.Text == anster)

        {

            Response.Write("回答正确！");

        }

        else

        {

            Response.Write("回答错误！");

        }

        TextBox3.Text = "";

        ti();

    }

}