c# windows应用程序

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;namespace shoupiao
{
    public partial class Form1 : Form
    {
      
        public Form1()
        {
             InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {        }        private void ticket_type_Combox_SelectedValueChanged(object sender, EventArgs e)
        {
            
            total_ticket_textBox.ReadOnly = false;
            payment_textBox.ReadOnly = false;
            receiving_textBox.Text = "";
            balance_textBox.Text = "";
            discount_groupBox.Enabled = false;
            switch (ticket_type_ComBox.SelectedIndex) 
            {
                case 0:
                    price_textBox.Text = string.Format("{0,f2}", commonprice);
                    break;
                case 1:
                    price_textBox.Text = string.Format("{0,f2}", commonprice*50/100);
                    break;
                case 2:
                    discount_groupBox.Enabled = true;
                    price_textBox.Text = string.Format("{0,f2}", commonprice * 90 / 100);
                    break;
            }
        }        private void textBox3_TextChanged(object sender, EventArgs e)
        {        }        private void balance_textBox_TextChanged(object sender, EventArgs e)
        {        }        private void button2_Click(object sender, EventArgs e)
        {
            Application.Exit();        }        private void radioButton1_CheckedChanged(object sender, EventArgs e)
        {
            
            
           price_textBox.Text = string.Format("{0,f2}", commonprice * 90 / 100);
        }        private void radioButton2_CheckedChanged(object sender, EventArgs e)
        {
            
            
         
            price_textBox.Text = string.Format("{0,f2}", commonprice * 80 / 100);
        }        private void radioButton3_CheckedChanged(object sender, EventArgs e)
        {
           
            
            
            price_textBox.Text = string.Format("{0,f2}", commonprice * 65 / 100);
        }       private void button1_Click(object sender, EventArgs e)
        {
            double payment, receiving, balance, price, commonprice;
            int tickets;
            try
            {
                tickets = Int32.Parse(total_ticket_textBox.Text);
                payment = double.Parse(payment_textBox.Text);
                price = double.Parse(price_textBox.Text);
                receiving = tickets * price;
                receiving_textBox.Text = string.Format("{0,f2}", receiving);
                balance = payment - receiving;
                balance_textBox.Text = string.Format("{0,f2}", balance);
            }
            catch 
            {
                MessageBox.Show("输入有误");
                return;
            }
        }        private void groupBox1_Enter(object sender, EventArgs e)
        {        }        private void label1_Click(object sender, EventArgs e)
        {        }     }
}
程序中运行结果说commonprice在上下文中不存在，那边怎么改?

Answer 1

很乱的代码
添加全局变量
private float commonprice = 0;

Answer 2

public Form1() 
        { 
            InitializeComponent(); 
        } 
前加1行
public static float commonprice =0;