Public
Class formSuma_de_4_en_4

 

Private
Sub cmdSuma_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSuma.Click

Dim i As
Integer, n As
Integer

Dim sn As
Single

Dim s As
Long

Dim st As
String

On
Error
GoTo Errors_cmdSuma

s = 0

st = ""

sn = Val(txtN.Text)

n = Int(sn)

If txtN.Text = ""
Then

Exit
Sub

ElseIf n <> sn Or n < 0 Or n > 30000 Then

MsgBox("Entra un número enter comprés entre 0 i 30.000", MsgBoxStyle.Exclamation)

txtN.Text = ""

Exit
Sub

End
If

For i = 1 To n - 4 Step 4

s = s + i

st = st + Str(i) + " + "

Next i

s = s + i

st = st + Str(i) + " = " + Str(s)

txtSuma.Text = st

Errors_cmdSuma:

Select
Case Err.Number

Case 0, 20 'No hi ha cap error

Case 6 'Overflow

MsgBox("Entra un número més petit", MsgBoxStyle.Information)

txtN.Text = ""

Exit
Sub

Case
Else

MsgBox("Error no previst: " + Str(Err.Number) + Err.Description)

On
Error
GoTo 0

Resume

End
Select

End
Sub

 

Private
Sub txtN_KeyUp(ByVal sender As
Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtN.KeyUp

Select
Case e.KeyValue 'Controlem l'entrada per teclat

Case 9, 16 To 20, 33 To 40, 44 To 46, 48 To 57, 91 To 93, 96 To 105, 110, 112 To 123, 144 To 145 'Tab, Ctrl-Alt, cursors, Del, 0 to 9, 0 To 9 teclat numèric, punt decimal, F1 to F12, Bloq Num-Bloq Despl

Case 13

Call cmdSuma_Click(sender, e)

Case 8, 27 'Esborrar amb BackSpace, Escape

Case
Else

'MsgBox("Entro: no número" + Str(e.KeyValue))

txtN.Text = ""

'If txtN.Text <> "" Then txtN.Text = Mid(txtN.Text, 1, Len(txtN.Text) - 1)

End
Select

End
Sub

 

Private
Sub txtN_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtN.TextChanged

txtSuma.Text = ""

End
Sub

End
Class