第六章 lesson6-4作业

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

namespace Lesson6_4
{
    /// <summary>
    ///减法类
    /// </summary>
    public class OperationJian:Operation
    {
        public override double GetResult()
        {
            double result = NumberA - NumberB;
            return result;
        }
    }
}

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

namespace Lesson6_4
{
    /// <summary>
    /// 加法类
    /// </summary>
    public class OperationAdd:Operation
    {
        public override double GetResult()
        {
            double result = NumberA + NumberB;
            return result;
        }
    }
}

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

namespace Lesson6_4
{
    /// <summary>
    /// 除法类
    /// </summary>
    public class OperationDiv:Operation
    {
        public override double GetResult()
        {
            if (NumberB == 0)
            {
                throw new Exception("除数不能为0!");
            }
            double result = NumberA / NumberB;
            return result;
        }
    }
}

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

namespace Lesson6_4
{
    /// <summary>
    /// 乘法类
    /// </summary>
     public class OperationChen:Operation
    {
         public override double GetResult()
         {
             double result = NumberA * NumberB;
             return result;
         }
    }
}

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

namespace Lesson6_4
{
    public class Operation
    {
        public double NumberA { get; set; }
        public double NumberB { get; set; }
        public virtual double GetResult()
        {
            double result = 0;
            return result;
        }
    }
}

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;

namespace Lesson6_4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.cmbfu.SelectedIndex = 0;//初始的运算符
        }
        /// <summary>
        /// 计算数值并判断
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnCalc_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(this.txtnum1.Text.Trim()))
            {
                MessageBox.Show("操作数不能为空！");
                this.txtnum1.Focus();
                return;
            }
            else if (string.IsNullOrEmpty(this.txtnum2.Text.Trim()))
            {
                MessageBox.Show("操作数不能为空！");
                this.txtnum2.Focus();
                return;
            }
            else
            {
                //计算数据
                try
                {
                    Operation opr = new Operation();
                    switch (this.cmbfu.SelectedItem.ToString().Trim())
                    {
                        case "+":
                            opr = new OperationAdd();
                            break;
                        case "-":
                            opr = new OperationJian();
                            break;
                        case "*":
                            opr = new OperationChen();
                            break;
                        case "/":
                            opr = new OperationDiv();
                            break;
                    }
                    opr.NumberA = double.Parse(this.txtnum1.Text.Trim());
                    opr.NumberB = double.Parse(this.txtnum2.Text.Trim());
                    this.lblCalc.Text = opr.GetResult().ToString();
                    this.lblJieguo.Visible = true;
                    this.lblCalc.Visible = true;
                }
                catch (Exception ex)
                {

                    MessageBox.Show("发生错误！" + ex.Message);
                }
            }
        }
    }
}