autocalculate total value of items in listview when removing item using c#

Question

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.

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();
}

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();
}

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

Could you, please, clarify what total you're asking. For me it did not open up, while reading the question. — mico
– mico, Commented Feb 15, 2014 at 19:28
I want the listview to act as a cart. I'm trying to get the total price of every item. — bluffer
– bluffer, Commented Feb 15, 2014 at 19:33

T.S. · Accepted Answer · 2014-02-15 19:50:56Z

1

Something like this

On the form level declare

private int _listTotal;

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();
}

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

}

Not tested but should work

edited Feb 15, 2014 at 19:50

answered Feb 15, 2014 at 19:44

T.S.

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11 Comments

bluffer Over a year ago

thanks for the help sir. Not really that accurate but it worked fine.

bluffer Over a year ago

Excuse me sir regarding to this program. My problem in the code you gave to me is that the every time I remove the item the value that it is removing is the 1st value added into the listview @T.S.

T.S. Over a year ago

@bluffer I just tested it - it works fine. I have list view with _l.MultiSelect = true;. I've added 10 items, selected 3 of them, for example items, 2,5,8. And they got removed perfectly by ` while (_l.SelectedItems.Count > 0) { _l.Items.Remove(_l.SelectedItems[0]);}` I see no problem. You need to actually click and select the item before removing it.

bluffer Over a year ago

thanks again sir hahaha. I tried using for loop and combined your code. But it now works fine thank you very much!!!!

T.S. Over a year ago

I warned you - don't use for-loop for mutating collections!! :o))

|

Lev K. · Accepted Answer · 2014-02-15 19:41:19Z

0

You can't change the same list in foreach.

foreach (ListViewItem item in lvCart.Items)
{
    if (lvCart.Items[0].Selected)
    {
        lvCart.Items.Remove(lvCart.SelectedItems[0]);
        total += Convert.ToInt32(item.SubItems[1].Text);
    }
}

The solution is create duplicate list and change it:

var newList = lvCart;

foreach (ListViewItem item in lvCart.Items)
{
    if (lvCart.Items[0].Selected)
    {
        newList.Items.Remove(lvCart.SelectedItems[0]);
        total += Convert.ToInt32(item.SubItems[1].Text);
    }
}

answered Feb 15, 2014 at 19:41

Lev K.

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Comments

Aftab Ahmed · Accepted Answer · 2014-02-15 19:48:23Z

0

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

      rtbTcost.Text = total.ToString();
   }

answered Feb 15, 2014 at 19:48

Aftab Ahmed

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