Listbox Control

[Bill Crawley]

Hi All,

I have populated a listbox control with some items and I then want to remove those selected by the user:

           foreach (ListItem li in ContactList.Items)
            {
                if (li.Selected == true)
                {
                    ContactList.Items.Remove(li.Text);
                }
            }

trouble is as soon as the first item is removed code crashes because the foreach is now out of sync.

HOw can I force only those items selected to be removed

[Peter_B]

The usual way to do this is to loop through the items in reverse - that way the removals do not affect the part of the collection which you still have to go through.

[BigEd781]

a ListBox has a SelectedItems property, use that and then remove each item in that collection.

[Bill Crawley]

Theres no SeletedItems Property only SelectedItem. I'll have a go with the reverse loop.

[BigEd781]

Yes there is

[Talikag]

It's not such a smart idea to change the size of list of items, during running on it in a for/foreach loop.
You could use the while loop instead:

int i = 0;
while(i < contactList.Items.Count)
{
   if(contactList.Items[i].Selected)
      contactList.Items.RemoveAt(i);
   else
      i++;
}

Alternatively:

for(int i=contactList.Items.Count-1; i>=0; i--)
{
     if(needToBeRemoved...)
        contactList.Items.RemoveAt(i);
}

[Bill Crawley]

BigEd, No there's not. It might be that because I'm using a Web Listbox that it's not there.

<asp:ListBox .....

Sorry guy's I forgot to say if it was windows or web.

[BigEd781]

BigEd, No there's not. It might be that because I'm using a Web Listbox that it's not there.

<asp:ListBox .....

Sorry guy's I forgot to say if it was windows or web.

Yes, that would be why. A standard WinForms ListBox has that property.