ASP.NET Datagrid Find Footer Controls

How to Find Control and convert to Text box, so we can manipulate data:
Find Header Controls

Ctype(Datagrid1.Controls(0).Controls(0).FindControl("txtInHeader"),TextBox)

Find Footer Controls

Ctype(Datagrid1.Controls(0).Controls(Datagrid1.Controls(0).Controls.Count - 1).FindControl("txtInFooter"),TextBox)

How To Summary data in DataGrid, for example :

Dim x As Integer
Dim dblTotalHour As Double = 0
Dim iTemTS As DataGridItem
For x = 0 To grdTimeSheet.Items.Count - 1
iTemTS = grdTimeSheet.Items(x)
dblTotalHour = dblTotalHour + CDbl(CType(iTemTS.FindControl(TextBoxTSHour), TextBox).Text) 'Count all
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