从列表中减去值时更新标签

Question

我有一个简单的应用程序，其中值被添加到列表框中，作为double的价格在项目的右侧作为字符串。我为标签编写了代码，每次将项目添加到列表框时都会增加价格。当我从列表框中删除选定项时，如何更新标签。

public void Form2_Load(object sender, EventArgs e)
    {

        foreach (Control butt in groupBox2.Controls)
        {
            if (butt is Button)
            {
                ((Button)butt).Click += Form2_Click;
            }
        }
    }

    public void Form2_Click(object sender, EventArgs e)
    {


        string st1 = ((Button)sender).Text;

        if (st1 == "Family_Pizza")
        {
            price = 22.95;

        }
       else if (st1 == "Large_Pizza")
        {
            price = 16.95;

        }
       else if (st1 == "Medium Pizza")
        {
            price = 11.95;

        }
       else if (st1 == "Small Pizza")
        {
            price = 7.95;

        }
        else if (st1 == "Garlic Bread")
        {
            price = 4.95;

        }
        else if (st1 == "BBQ Ribs")
        {
            price = 9.95;

        }
        else if (st1 == "BBQ Wings")
        {
            price = 9.95;

        }
        else if (st1 == "Express Combo")
        {
            price = 5.95;

        }
        else if (st1 == "1.25 L Drink")
        {
            price = 4.50;

        }
        else if (st1 == "375 ml Drink")
        {
            price = 2.60;

        }
        else if (st1 == "600 ml Drink")
        {
            price = 3.50;

        }
        else if (st1 == "Ben 'n' Jerry Core")
        {
            price = 13.50;

        }
        else if (st1 == "Ben 'n' Jerry Pint")
        {
            price = 11.95;

        }


        s2 = price.ToString("C");


        string item = st1;
        string value=s2.PadLeft(s2.Length+8,' ');


        listBox1.Items.Add(item+value);
        updprice = price + updprice;
        label2.Text = updprice.ToString("C");

    }


private void button3_Click(object sender, EventArgs e)
{
    listBox1.Items.Remove(listBox1.SelectedItem);
}

Answer 1

在您的活动button3_Click，您需要在删除列表框项目之前设置标签值：

private void button3_Click(object sender, EventArgs e) {
  double price = 0;
  if (listBox1.SelectedItem.ToString().IndexOf("Family_Pizza") > -1) {
    price = 22.95;
  }
  .
  .
  . 
  else if (listBox1.SelectedItem.ToString().IndexOf("Ben 'n' Jerry Pint") > -1) {
    price = 11.95;
  }

  double label_value = Convert.ToDouble(label2.Text.Replace("$", ""));
  label_value -= price;
  label2.Text = label_value.ToString("C");
  listBox1.Items.Remove(listBox1.SelectedItem);
}