Imagebutton click in Gridview

<asp:templatefield xmlns:asp="#unknown">
  <itemtemplate>
    <asp:button id="AddButton" runat="server">
      CommandName="AddToCart" 
      CommandArgument="<%# ((GridViewRow) Container).RowIndex %>"
      Text="Add to Cart" />
  </asp:button></itemtemplate> 
</asp:templatefield>


protected void GridView1_RowCommand(object sender, 
  GridViewCommandEventArgs e)
{
  if (e.CommandName == "AddToCart")
  {
    // Retrieve the row index stored in the 
    // CommandArgument property.
    int index = Convert.ToInt32(e.CommandArgument);
    // Retrieve the row that contains the button 
    // from the Rows collection.
    GridViewRow row = GridView1.Rows[index];
    // Add code here to add the item to the shopping cart.
  }
  }