checkboxlist取值的问题

Question

string str_SelectedColumn="";
for (int i=0;i<chkl_ShowSelectColumn.Items.Count;i++)
{
                //chkl_ShowSelectColumn.Items[i].Selected=true;
if (chkl_ShowSelectColumn.Items[i].Selected==true)
{
if (str_SelectedColumn!="")
{
                        str_SelectedColumn+=" , ";
}
                    str_SelectedColumn+=chkl_ShowSelectColumn.Items[i].Value+" as "+chkl_ShowSelectColumn.Items[i].Text;
}
}
if (str_SelectedColumn=="")
{
Response.Write("<script>alert('选择显示字段不能为空');</script>");
return;
}

Answer 1

为什么选择了str_SelectedColumn 始终是""
asp:panel id="ShowSelectColumn" style="LEFT: 0px; OVERFLOW: auto; POSITION: absolute; TOP: 50px"
Height="400px" Runat="server">
<asp:CheckBoxList id="chkl_ShowSelectColumn" Runat="server" Font-Size="9" RepeatColumns="1" AutoPostBack="false"></asp:CheckBoxList>
</asp:panel>

Answer 2

大家帮我看看
string str_SelectedColumn="";
for (int i=0;i<chkl_ShowSelectColumn.Items.Count;i++)
{
if (chkl_ShowSelectColumn.Items[i].Selected==true)
{
if (str_SelectedColumn!="") str_SelectedColumn+=" , ";
 str_SelectedColumn+=chkl_ShowSelectColumn.Items[i].Value+" as "+chkl_ShowSelectColumn.Items[i].Text;
}
}
if (str_SelectedColumn=="")
{
Response.Write("<script>alert('选择显示字段不能为空');</script>");
return;
}

Answer 3

string str_SelectedColumn="";
你这个值初试化始终为空得！改成这样吧str_SelectedColumn="";
for (int i=0;i<chkl_ShowSelectColumn.Items.Count;i++)
{
if (chkl_ShowSelectColumn.Items[i].Selected==true)
{ str_SelectedColumn+=","+chkl_ShowSelectColumn.Items[i].Value+" as "+chkl_ShowSelectColumn.Items[i].Text;
}
if (str_SelectedColumn.length<1)
{
Response.Write("<script>alert('选择显示字段不能为空');</script>");
return;
}

Answer 4

我发现问题了 ，页面加载的时候我忘记!Page.IspostBack了