How to get row index by checking a checkbox in a gridview

In this Code i will show how to get row index of the gridview when a check box is clicked.

first,we need a gridview containing checkbox as template column in it.When ever a check box is clicked ,we should get row index for the gridview.
so in design view create a gridview like this

 
 < asp:GridView ID="gdview" runat="server" AutoGenerateColumns="False" >  
 < Columns >  
 < asp:TemplateField >  
 < ItemTemplate >  
 < asp:CheckBox ID="chk" runat="server" AutoPostBack="true" Text='< %#Eval("CAT_NAME") % >‘ OnCheckedChanged="Check_Clicked"/ >
  < /ItemTemplate >  
 < /asp:TemplateField >  
 < /Columns >  
 < /asp:GridView >  

 
protected void Check_Clicked(Object sender, EventArgs e)
{
CheckBox ck1 = (CheckBox) sender;
GridViewRow grow = (GridViewRow)ck1.NamingContainer;
Response.Write("You selected row " + ((CheckBox)grow.FindControl("chk")).Text);
}