Dim Boxes(31) As TextBox
 
Private Sub Form_Load(....)
Initialize
End Sub
 
Private Sub Initialize()
Dim Tb as TextBox
 
Boxes(0) = TextBox32
'...
'...
'...
Boxes(31) = TextBox1
 
For Each Tb in Boxes
AddHandler Tb.Click, Addressof Boxes_Click
Next
End Sub
 
Private Sub Boxes_Click(......)
Dim Tb As TextBox = CType(sender, TextBox)
 
If Tb.Text = "" then Tb.Text = 0     'Hier ist mein Problem
End Sub