Question

for (int counter = 0; counter < countSelected; counter++)
        {
            string groupName = txt_GroupName.Text;
            //Get GroupID from the created group
            string GroupIDQueryText = "SELECT GroupID FROM tbl_group WHERE GroupName ";
            int groupID = Convert.ToInt32(server.performQuery(GroupIDQueryText, groupName, MySqlDbType.VarChar));
            //To get User ID
            string firstName = ListBoxMembers.SelectedItems[counter].Value;
       }

This isn’t returning the selected value, but instead returns the 1st person in the list even if I haven’t selected it. Where am I going wrong?
System.Web.UI.WebControls does not contain defenition for listboxmembers.selectedItems error

Answer 1

You are using .Items which is the collection of all items in the ListBox. I think you intend to use .SelectedItems (documentation on MSDN).

// When counter = 0, this is the very first item in the listbox
ListBoxMembers.Items[counter].Value;

// When counter = 0, this is the first of the selected items in the listbox
ListBoxMembers.SelectedItems[counter].Value;

EDIT Web ListBox controls are different than WinForms ListBox controls, so knowing that context is very valuable. Here’s an article from MSDN on how to determine the selected items in a multi-selection list control (scroll down to the multi-selection section). The idea is to loop through all .Items and check the .Selected property on each.