Do code in VB.net on text input before text being shown - vb.net

Question

I have this code in VB6:
Private Sub t_Change(Index As Integer)
Iznos = 0
For i = 1 To 4
Iznos = Iznos + t(i).Text
Next
If CDbl(Iznos) > Label13.Caption Then
t(Index).Text = 0
Iznos = 0
t(Index).SelStart = 0
t(Index).SelLength = 1
For i = 1 To 4
Iznos = Iznos + t(i).Text
Next
End If
t(0).Text = Format(Label13.Caption - CDbl(Iznos), "#,##0.00")
End Sub
This code works for my textboxes (4 of them named: t(0),t(1),t(2),t(3)).
I am trying to achieve the same with VB.net but i can't seem to wrap my head around it.
This is my code in VB.Net:
Public Function izracunaj(ByVal s As Object)
Dim ukupniIznos As Decimal = Decimal.Parse(maticnavalutatbox.Text)
Dim poslaniIznos As Decimal = Decimal.Parse(s.text)
Dim iznos As Decimal
Dim allTextboxesPayment() As TextBox = {gotovinaTbox, karticeTbox, ostaloTbox, ziralnoTbox}
For Each kontrola As TextBox In allTextboxesPayment
iznos = iznos + Decimal.Parse(kontrola.Text)
Next
If CDbl(iznos) > ukupniIznos Then
s.Text = 0
iznos = 0
For Each kontrola As TextBox In allTextboxesPayment
iznos = iznos + Decimal.Parse(kontrola.Text)
Next
End If
gotovinaTbox.Text = Format(ukupniIznos - CDbl(iznos), "#,##0.00")
End Function
But if I call my function like this:
Private Sub ziralnoTbox_TextChanged(sender As Object, e As TextChangedEventArgs) Handles ziralnoTbox.TextChanged
izracunaj(sender)
End Sub
It does not work because my izracunaj function already has the input value of ziralnoTbox. How can i achieve same functionality with vb.net as in vb6

Answer 1

If I'm looking at this correctly, you could make use of the TextChanged event.
Private Sub TextBox1_TextChanged(sender As Object,
e As EventArgs) Handles gotovinaTbox.TextChanged,
karticeTbox.TextChanged,
ostaloTbox.TextChanged,
ziralnoTbox.TextChanged
Dim ukupniIznos As Decimal = Decimal.Parse(maticnavalutatbox.Text)
Dim poslaniIznos As Decimal = Decimal.Parse(s.text)
Dim iznos As Decimal
Dim allTextboxesPayment() As TextBox = {gotovinaTbox, karticeTbox, ostaloTbox, ziralnoTbox}
'gotovinaTbox, quita esto?
For Each kontrola As TextBox In allTextboxesPayment
iznos = iznos + Decimal.Parse(kontrola.Text)
Next
If CDbl(iznos) > ukupniIznos Then
s.Text = 0
iznos = 0
For Each kontrola As TextBox In allTextboxesPayment
iznos = iznos + Decimal.Parse(kontrola.Text)
Next
End If
gotovinaTbox.Text = Format(ukupniIznos - CDbl(iznos), "#,##0.00")
End Sub