CheckBoxListen Seçilen Itemları Aralarında Virgül Koyarak Saklamak

  <asp:CheckBoxList ID="chkboxlist1 runat="server">
<asp:ListItem Value="ifade1">ifade1</asp:ListItem>
<asp:ListItem Value="ifade2">ifade2</asp:ListItem>
<asp:ListItem Value="ifade3">ifade3</asp:ListItem>
<asp:ListItem Value="ifade4">ifade4</asp:ListItem>
<asp:ListItem Value="ifade5">ifade5</asp:ListItem>
</asp:CheckBoxList>

  string secilen_ifadeler= "";
for (int i = 0; i < chkboxlist1 .Items.Count; i++)
{
if (chkboxlist1.Items[i].Selected == true)
{
secilen_ifadeler+= chkboxlist1.Items[i].Text.ToString() + " , ";
}
}