Question

I have 14 Dropdownlist accroding to 7 Days.
Like For a day First dropdown list is Named as From-Time and Second Dropdown list is To-Time.
List Values are Set by 30 minutes Time Difference.
To-Time dropdownlist Should save only those list items which fall after From-time Dropdownlist.like if i select 1 Pm by first then second dropdown list should carry list-items after 1 Pm.
removing is done like this..

 protected void ddlMonst_SelectedIndexChanged(object sender, EventArgs e)
        {
            RemoveListItem(sender as DropDownList,checkboxes);
        }
        private void RemoveListItem(DropDownList DDl,DropDownList[] checkboxes)
        {
            int CurrrentSelectedIndex = DDl.SelectedIndex;
            String StartDDlName = DDl.ID.Substring(3, 3).ToString() + "ed";
           String TargetedDDlName = string.Empty;
            for (int i = 0; i < checkboxes.Length; i++)
            {
                TargetedDDlName = checkboxes[i].ID.Substring(3, 5).ToString() ;
                if (StartDDlName.Equals(TargetedDDlName))
                {
                    for(int j=0 ;j<CurrrentSelectedIndex;j++)
                    checkboxes[i].Items.RemoveAt(0);
                }

            }

        }

but this logic fails if i selected again and again from First Dropdown list.It reomoves all from second one.

How to Handle this situation

Answer 1

Assuming your code is successfully removing the Items, then it makes sense that the To-Time DropDowns could end up being empty after multiple successive selects from the From-Time DropDown(s).

Instead of using .RemoveAt(), you could .Clear() your To-Time DropDowns and then .Add() the Items from the From-Time DropDown from its SelectedIndex and onwards.

    // ...
    // get reference to To/From DropDown(s) here
    // ...
    dd_time_to.Items.Clear();
    for (int i = dd_time_from.SelectedIndex; i < dd_time_from.Items.Count; i++)
    {
        dd_time_to.Items.Add(dd_time_from.Items[i]);
    }

You’ll have to modify this to work on your DropDownList[]