Get value from GridView when a button is clicked

I have a GridView , and the GridView has an item template. Now I need to get the value of the first cell which contains the value I need but I have tried the following and does not work, it eturns a ""

 int id = Convert.ToInt32(GridView.Rows[index].Cells[0].Text);

Here is the code I have in the gridview

<Columns>
   <asp:TemplateField HeaderText="ID"开发者_如何学JAVA>
         <ItemTemplate>
             <asp:Label runat="server" ID="lblDepartmentID" Text='<%#DataBinder.Eval(Container.DataItem,"DepartmentID")%>' />
                                        </ItemTemplate>
                                        <HeaderStyle HorizontalAlign="Left" />
      </asp:TemplateField>

I have to emphazise that I do not want to use the GridView_RowCommand or other GridView events.. I need to pull this value upon clicking a button on the same page.

How can I do this?

If you are trying to access the text value of Label then you have to first get the reference to Label control like this:

Label lbl = (Label)GridView.Rows[index].FindControl("lblDepartmentID");

and then use it's Text property to get the value required:

int id = Convert.ToInt32(lbl.Text);