listbox之间item的添加和移除

微软quickstart提供的

<asp:listbox id="AvailableFonts" width="100px" runat=server>
                    <asp:listitem>Romanasp:listitem>
                    <asp:listitem>Arial Blackasp:listitem>
                    <asp:listitem>Garamondasp:listitem>
                    <asp:listitem>Somonaasp:listitem>
                    <asp:listitem>Symbolasp:listitem>
                 asp:listbox>

 void RemoveAllBtn_Click(Object Src, EventArgs E) {

            while (InstalledFonts.Items.Count != 0) {

               AvailableFonts.Items.Add(new ListItem(InstalledFonts.Items[0].Value));
               InstalledFonts.Items.Remove(InstalledFonts.Items[0].Value);
            }
        }
当数据源改为

<asp:listbox id="AvailableFonts" width="100px" runat=server>
                    <asp:listitem value="1">Romanasp:listitem>
                    <asp:listitem value="bbb">Arial Blackasp:listitem>
                    <asp:listitem value="333">Garamondasp:listitem>
                    <asp:listitem value="4">Somonaasp:listitem>
                    <asp:listitem value="5">Symbolasp:listitem>
                 asp:listbox>

listbox.items.count会一直为总数，不会顺while循环的变化，可以修改为如果方法：

  #region button

  private void btnRemoveAll_Click(object sender, System.EventArgs e)
  {
   while (lstSelDpt.Items.Count != 0)
   {
    lstAllDpt.Items.Add(lstSelDpt.Items[lstSelDpt.Items.Count-1]);
    lstSelDpt.Items.RemoveAt(lstSelDpt.Items.Count-1);
   }

  }

  private void btnRemove_Click(object sender, System.EventArgs e)
  {
   while(lstSelDpt.SelectedIndex != -1)
   {
    lstAllDpt.Items.Add(lstSelDpt.Items[lstSelDpt.SelectedIndex]);
    lstSelDpt.Items.Remove(lstSelDpt.Items[lstSelDpt.SelectedIndex]);
   }
  }

  private void btnAdd_Click(object sender, System.EventArgs e)
  {   
   while (lstAllDpt.SelectedIndex != -1)
   {
    lstSelDpt.Items.Add(lstAllDpt.Items[lstAllDpt.SelectedIndex]);
    lstAllDpt.Items.Remove(lstAllDpt.Items[lstAllDpt.SelectedIndex]);
   }
  }

  private void btnAddAll_Click(object sender, System.EventArgs e)
  {
   while (lstAllDpt.Items.Count != 0)
   {
    lstSelDpt.Items.Add(lstAllDpt.Items[lstAllDpt.Items.Count-1]);
    lstAllDpt.Items.Remove(lstAllDpt.Items[lstAllDpt.Items.Count-1]);
   }

  }

  #endregion