asp.net中的列表框控件

Question

I have two listbox controls Listbox1 and Listbox2. I want to get the count of items of Listbox2 which are selected from Listbox1 in c#? Suppose i have total 7 items in Listbox1 and from those i have selected only 3 items in Listbox2 control. I want to get the count of items of Listbox2 in C#?

Answer 1

Wonder why nobody used Linq.

---

@Riya: I understand your requirement as, you want the Count of SelectedItems in ListBox1 that are present in ListBox2 Items . If so do this.

var filteredListCount = ListBox2.Items
    .Cast<ListItem>()
    .Where(li => 
        ListBox1.Items
            .Cast<ListItem>()
            .Where(item => item.Selected)
            .Select(item => item.Text).Contains(li.Text))
    .Count();

Answer 2

Loop thru the selected items when the selection is changed

Something like this:

     int count = 0;    
        foreach(string itemListbox2 in listBox2.Items)
        {
            if (itemListbox2.Selected)
            {    
                 foreach(string itemListbox1 in listbox1.Items)
                 {
                   if (itemListbox1.Selected)
                   {
                      if(itemListbox1.Equals(itemListbox2))
                      {
                        count++;
                        break;
                      }
                   }
                }
            }
        }

Answer 3

您可以循环遍历ListBox1中的所有选定项目，并在循环内部搜索ListBox2中具有相同值的项目，如果选中了该项目，则可以增加一个计数器。

Answer 4

A Listbox in asp.net doesn't have SelectedItems. Therefor loop through the Items and check if they are selected. If so, find an item in the other list with the same value. If you find a corresponding item, count it. Like this:

int count = 0;
foreach (ListItem item in secondListBox.Items)
{
    if (item.Selected)
    {
        ListItem itemWithSameValue = firstListBox.Items.FindByValue(item.Value);
        if (itemWithSameValue != null)
        {
            count++;
        }
    }
}