四则运算《《《代码封装 策略模式

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace sum
{
    class Class1
    {
        public interface Calculator        //声明计算接口
        {
            double Cal(double x, double y);
        }
        private double x;                //定义x变量；

        public double X                  //封装字段
        {
            get { return x; }
            set { x = value; }

        }
        private double y;               //定义y变量


        public double Y                  //封装字段
        {
            get { return y; }
            set { y = value; }

        }
        public class Add : Calculator            //接口法运算
        {
            public double Cal(double x, double y)
            {
                double result = 0;
                result = x + y;
                return result;
            }
        }
        public class Sub : Calculator 
        {
            public double Cal(double x, double y)
            {
                double result = 0;
                result = x - y;
                return result;
            }
        }
        public class Mul : Calculator 
        {
            public double Cal(double x, double y)
            {
                double result = 0;
                result = x * y;
                return result;
            }
        }
        public class Div : Calculator  
        {
            public double Cal(double x, double y)
            {
                double result = 0;
                result = x / y;
                return result;
            }
        }
        public class Opear                  //定义运算符  
        {
            private Calculator calculate;
            public Opear(Calculator calculate)
            {
                this.calculate = calculate;
            }
            public double Cal(double x, double y, String op)  //返回运算结果
            {
                return this.calculate.Cal(x, y);
            }
        }
    }
}

策略模式引用：

 private void textBox8_KeyDown(object sender, KeyEventArgs e)
        {
            sum.Class1.Opear opear = null;
            double x = Convert.ToDouble(textBox5.Text); //为相关的变量赋值
            double y = Convert.ToDouble(textBox7.Text);
            string op = textBox6.Text;
            switch (op)
            {
                case "+":
                     opear = new  sum.Class1.Opear(new sum.Class1.Add()); //策略模式的引用
                    break;
                case "-":
                    opear = new sum.Class1.Opear(new sum.Class1.Sub());

                    break;
                case "*":
                    opear = new sum.Class1.Opear(new sum.Class1.Mul());

                    break;
                case "/":
                    opear = new sum.Class1.Opear(new sum.Class1.Div());

                    break;
                default:
                    break;
            }
            
            if (e.KeyCode == Keys.Enter)
            {
                string answer = opear.Cal(x, y, op).ToString();
                if (textBox8.Text ==answer.ToString())
                {
                    MessageBox.Show("回答正确");
                    Count++;
                    Right++;
                }
                else
                {
                    MessageBox.Show("回答错误");
                    Count++;
                }

运行结果：

保存出好的题