使用C＃删除项目时autocalculate列表视图中的项目总价值 [英] autocalculate total value of items in listview when removing item using c#

问题描述

我用一个ListView作为一个购物车。我需要知道如何重新计算车的总价值时，我删除项目。

I'm using a listview as a shopping cart. I need to know how to recalculate the total value of the cart when I remove an item.

下面是我的code添加到列表视图;

Here is my code for adding to listview;

private void btnACart_Click(object sender, EventArgs e)
{
    int value = 0;

    for (int i = 0; i < lvCart.Items.Count; i++)
    {
        value += int.Parse(lvCart.Items[i].SubItems[1].Text);
    }

    rtbTcost.Text = value.ToString();
}

下面是我的code去除项目：

Here is my code for removing items:

private void btnRemoveItem_Click(object sender, EventArgs e)
{
    int total = 0;
    foreach (ListViewItem item in lvCart.Items)
    {
        if (lvCart.Items[0].Selected)
        {
            lvCart.Items.Remove(lvCart.SelectedItems[0]);
            total += Convert.ToInt32(item.SubItems[1].Text);
        }
    }

    rtbTcost.Text = total.ToString();
}

我要重新计算一个项目被删除的项目的总价值。我应该怎么办呢？

I want to recalculate the total value of items an item is removed. How should I do that?

推荐答案

像这样

在形式层面申报

private int _listTotal;

添加 - 我想在这里你有一些问题，因为您应该添加到总当您添加的项目

Adding - I think here you have some problems because you should add to total when you add the item

private void btnACart_Click(object sender, EventArgs e)
{
    int value = 0;

    for (int i = 0; i < lvCart.Items.Count; i++)
    {
        value += int.Parse(lvCart.Items[i].SubItems[1].Text);
    }
    // how about lvCart.Items.Add(<myVal>)...???
    _listTotal += value; // and here add myVal
    rtbTcost.Text = _listTotal.ToString();
}

然后在取出时 - 你不希望使用任何for循环上的变异集合。但是，而上的突变完美的作品

Then when removing - you don't want to use any "for-loops" on mutating collection. But "while" works perfectly on mutations

private void btnRemoveItem_Click(object sender, EventArgs e)
{
    int totalRemoved = 0;
    while (lvCart.SelectedItems.Count > 0)
    {
        totalRemoved += Convert.ToInt32(lvCart.SelectedItems[0].SubItems[1].Text);
        lvCart.Items.Remove(lvCart.SelectedItems[0]);
    } 
    _listTotal -= totalRemoved;
    rtbTcost.Text = _listTotal.ToString

}

未经测试，但应该工作

Not tested but should work

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