Textbox arguments and converting decimal and binary numbers - vba

Question

For school, I have to make a program which converts a binary number to a decimal number and backwards. I want to make it so it changes whenever you type something in the textboxes.
Whenever I type something, I get the error that I should click either of the textboxes triggered by the last 'Else'.
TextBox1 is the textbox containing the decimal number, and TextBox2 contains the binary number.
This is the code:
Public Sub DecBinConverter_Activate()
Dim x As Double
Dim i As Long
Dim Active As String
Active = "TextBox1"
End Sub
Private Sub TextBox1_Change()
Call ConvertDecBin
End Sub
Private Sub TextBox2_Change()
Call ConvertDecBin
End Sub
Public Sub TextBox1_Enter()
Active = "TextBox1"
End Sub
Public Sub TextBox2_Enter()
Active = "TextBox2"
End Sub
Public Sub ConvertDecBin()
If Active = "TextBox1" Then
If TextBox1.Text <> "" Then
If IsNumeric(TextBox1.Text) Then
x = Round(Val(TextBox1.Text), 0)
If x < 10000000000# Then
TextBox1.Text = x
TextBox2.Text = Trim(Str(x Mod 2))
If (x Mod 2) = 0 Then
x = x / 2
Else
x = (x - 1) / 2
End If
Do While x <> 0
TextBox2.Text = Trim(Str(x Mod 2)) & TextBox2.Text
If (x Mod 2) = 0 Then
x = x / 2
Else
x = (x - 1) / 2
End If
Loop
Else
TextBox2.Text = "ERROR: Overload (0-999999999)"
End If
Else
TextBox2.Text = "ERROR: You must fill in a decimal number"
End If
End If
ElseIf Active = "TextBox2" Then
If TextBox2.Text <> "" Then
If IsNumeric(TextBox2.Text) Then
If Len(Str(TextBox2.Text)) > 40 Then
TextBox1.Text = "ERROR: Fill in a number no longer than 40 characters!"
Else
If InStr(Str(TextBox2.Text), "2") Or InStr(Str(TextBox2.Text), "3") Or InStr(Str(TextBox2.Text), "4") Or InStr(Str(TextBox2.Text), "5") Or InStr(Str(TextBox2.Text), "6") Or InStr(Str(TextBox2.Text), "7") Or InStr(Str(TextBox2.Text), "8") Or InStr(Str(TextBox2.Text), "9") Then
TextBox1.Text = "ERROR: You must fill in a binary number!"
Else
x = Round(Val(TextBox2.Text), 0)
TextBox2.Text = x
TextBox1.Text = 0
For i = 1 To Len(Str(x))
If Mid(Str(x), i, 1) = "1" Then
TextBox1.Text = TextBox1.Text * 2 + 1
Else
TextBox1.Text = TextBox1.Text * 2
End If
Next i
End If
End If
Else
TextBox1.Text = "ERROR: You must fill in a binary number!"
End If
End If
Else
MsgBox "An unknown error occurred, please click either of the textboxes.", vbOKOnly, "ERROR"
End If
End Sub

Answer 1

A couple of comments on your code:
You don't need to have an "Active" field because your event routines
are assigned to a control.
Anytime you work on a textbox field, the "Change" event is executed.
You would have to handle that (I can't find a link for that).
I recommend using "Option Explicit ".
Everybody has their own style; I hope this helps you:
Option Explicit
' Textbox1 has decimal, textbox2 has binary
Private Sub TextBox1_KeyDown(ByVal KeyCode As MSForms.ReturnInteger, ByVal Shift As Integer)
Dim idec&, s1$
If KeyCode <> 13 Then Exit Sub ' Only act upon "Enter"
s1 = TextBox1.Value
If s1 = "" Then Exit Sub ' blank ok
If Not IsNumeric(s1) Then
MsgBox "Textbox1 is not numeric"
TextBox1.Value = ""
Exit Sub
End If
' -- decimal to binary
idec = Val(s1) ' have decimal number
s1 = "" ' start binary string
Do While idec > 0
If idec Mod 2 = 1 Then s1 = s1 & "1" Else s1 = s1 & "0"
idec = idec \ 2 ' integer divide
Loop
TextBox2.Value = s1
End Sub
Private Sub TextBox2_KeyDown(ByVal KeyCode As MSForms.ReturnInteger, ByVal Shift As Integer)
Dim idec&, ibin&, ixch&, ch$, s1$
If KeyCode <> 13 Then exit Sub ' Only act upon "Enter"
s1 = TextBox2.Value
If s1 = "" Then Exit Sub ' blank ok
If Not IsNumeric(s1) Then
MsgBox "Textbox2 is not numeric"
TextBox2.Value = ""
Exit Sub
End If
idec = 0 ' start decimal number
For ixch = 1 To Len(s1) ' binary to decimal
ibin = Val(Mid$(s1, ixch, 1)) ' 0 or 1
If ibin < 0 Or ibin > 1 Then
MsgBox "Textbox2 is not binary"
TextBox2.Value = ""
Exit Sub
End If
idec = idec * 2 + ibin
Next ixch
TextBox1.Value = Str$(idec)
End Sub