本人是初学,想问一下一下一个计算打折的程序任何 实现

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;namespace WindowsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }        private void button1_Click(object sender, EventArgs e)
        {
            decimal price, discount;
            try
            {
               
                price = Convert.ToDecimal(Input.Text);
                if (price >= 2000)
                {
                    discount = price * 0.8m;
                }
                else if (price >= 1000 && price < 2000)
                {
                    discount = price * 0.85m;
                }
                else if (price >= 500 && price < 1000)
                {
                    discount = price * 0.9m;
                }
                else if (price >= 100 && price < 500)
                {
                    discount = price * 0.95m;
                }                discount = Convert.ToDecimal(....);//这里不太会定义
                if (discount >= 0)
                {
                    result.Text = String.Format("{0:C}", discount);
                }
                else
                    result.Text = "请输入整数";
            }
            catch
            {
                result.Text = "输入有错，请重输！";
            }
        }        private void button3_Click(object sender, EventArgs e)
        {
            this.Hide();
            Program.f2.Show();
        }        private void button2_Click(object sender, EventArgs e)
        {
            Input.Text = "";
            result.Text = "";
        }
    }
}