在 ListView 中删除时减少总量

Question

我有一个 ListView 和一个按钮。当我点击它时，它会在我的标签中添加一个（名称、价格、数量、总计）和总金额，问题是当我在 ListView 中删除选中的项目时如何减少标签中的总金额

顺便说一句，我的总计和价格数据类型不是在按钮内部的形式，按钮内部是价格、总计和计算的金额。

这是 ListView 的删除按钮

private void button4_Click(object sender, EventArgs e)
{
    if (listView1.CheckedItems.Count > 0)
    {
        var confirmation = MessageBox.Show("Are you sure?", "Confirmation",
            MessageBoxButtons.YesNo);

        if (confirmation == DialogResult.Yes)
        {
            for (int i = listView1.CheckedItems.Count - 1; i >= 0; i--)
            {
                ListViewItem itm = listView1.CheckedItems[i];
                listView1.Items[itm.Index].Remove();
                label5.Text = "0"; //label for total amount
            }
        }
        else
        {
        }
    }
}

这是在ListView中添加项目的代码

private void addItem_Click(object sender, EventArgs e)
{
    ListViewItem item = listView1.FindItemWithText("Cola");

    if (String.IsNullOrEmpty(textBox2.Text))
    {
        MessageBox.Show("Enter Quantity", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        textBox2.Text = "";
    }
    else if (textBox2.Text == "0")
    {
        MessageBox.Show("Enter Valid Quantity", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
    }
    else if (item != null)
    {
        price = 500;
        quantity = Double.Parse(textBox2.Text);
        total = price * quantity;
        item.SubItems[2].Text = quantity.ToString();
        item.SubItems[3].Text = total.ToString();
        textBox2.Text = "";
        totalAll = total + total2;
        label5.Text = totalAll.ToString();
    }
    else if (item == null)
    {
        price = 500;
        quantity = Double.Parse(textBox2.Text);
        total = price * quantity;
        String[] row = { label1.Text, price.ToString(), quantity.ToString(), total.ToString() };
        item = new ListViewItem(row);
        listView1.Items.Add(item);
        textBox2.Text = "";
        totalAll = total + total2;
        label5.Text = totalAll.ToString();
    }
}

Answer 1

如果您要保留 ListBox 中所有项目的总和，则只需减去要删除的项目的总和：

// Subtract selected item total from grand total
// This assumes that your 'totalAll` variable is a class-level double variable 
// and that the item total is stored in the `Text` property of itm.SubItems[3]
totalAll = totalAll - double.Parse(itm.SubItems[3].Text); 

label5.Text = totalAll.ToString();

Answer 2

在循环之后，我将它设置为当前的项目数：

if ( ...confirm... )
{
    for ( ... )
    {
    }

    label5.Text = listView1.Items.Count.ToString();
}