For Each ctl As Control In Me.Controls
If (ctl.Name.StartsWith("lbl")) AndAlso (TypeOf ctl Is Label) Then
Dim lbl As Label = DirectCast(ctl, Label)
lbl.Text = ""
End If
Next ctl
Dim lbltest As Label
For i = 1 To 10
lbltest = DirectCast(TabPage3.Controls("lbltest" & i.ToString), Label)
If lbltest IsNot Nothing Then
lbltest.Text = "xxxx"
End If
Next i