(深入.Net平台和C#编程)第六章上机练习4.李向阳.20170411

==============加法类================
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sj4.Entity
{
    /// <summary>
    /// 加法
    /// </summary>
    public class Jiafa : Operation
    {
        //计算方法
        public override double GetResult()
        {
            if (NumberB == 0)
            {
                throw new Exception("不能为0");
            }
            double result = NumberA + NumberB;
            return result;
        }
    }
}

============减法类============
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sj4.Entity
{
    /// <summary>
    /// 减法
    /// </summary>
    public class Jianfa : Operation
    {
        //计算方法
        public override double GetResult()
        {
            double result = NumberA - NumberB;
            return result;
        }
    }
}

=========乘法类===============
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sj4.Entity
{
    /// <summary>
    /// 乘法类
    /// </summary>
    public class Cehng : Operation
    {
        //计算方法
        public override double GetResult()
        {
            if (NumberA == 0)
            {
                throw new Exception("不能为0");
            }
            double result = NumberA * NumberB;
            return result;
        }
    }
}

===============除法类==============
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sj4.Entity
{
    /// <summary>
    /// 除法
    /// </summary>
    public class Chufa : Operation
    {
        //计算方法
        public override double GetResult()
        {
            if (NumberB == 0)
            {
                throw new Exception("不能为0");
            }
            double result = NumberA / NumberB;
            return result;
        }
    }
}

================测试类==================
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;
using Sj4.Entity;

namespace Sj4
{
    public partial class FrmMain : Form
    {
        public FrmMain()
        {
            InitializeComponent();
        }
        //加载事件
        private void FrmMain_Load(object sender, EventArgs e)
        {
            cmbAdd();
        }
        /// <summary>
        /// 添加运算符
        /// </summary>
        public void cmbAdd()
        {
            cmbList.Text = "+";
            cmbList.Items.Add("-");
            cmbList.Items.Add("*");
            cmbList.Items.Add("/");
        }
        /// <summary>
        /// 计算点击事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnJiSuan_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(txt1.Text.Trim()) && string.IsNullOrEmpty(txt2.Text.Trim()))
            {
                MessageBox.Show("不能为空");
            }
            Operation bb = new Operation();
            switch (cmbList.Text.Trim())
            {
                case "+":
                    bb = new Jiafa();
                    break;
                case "-":
                    bb = new Jianfa();
                    break;
                case "/":
                    bb = new Chufa();
                    break;
                case "*":
                    bb = new Cehng();
                    break;
            }
            bb.NumberA = double.Parse(txt1.Text.Trim());
            bb.NumberB = double.Parse(txt2.Text.Trim());
            this.lblJg.Text = bb.GetResult().ToString();
        }
    }
}