Binaryworld - Floating Point Numbers Validation ... [ VB -> String ]

Private Sub Form_Load()
  Text1.Text = Empty
End Sub

' USAGE
'Create a form a text box
Private Sub Text1_KeyPress(KeyAscii As Integer)
  ' Precision is 2 in this case
  ' Send the Precision Value same in both the Functions
  Call ValidateNum(Text1, 2, KeyAscii)
End Sub

Private Sub Text1_KeyUp(KeyCode As Integer, Shift As Integer)
  Call ValidateDel(Text1, 2, KeyCode)
End Sub

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Option Explicit
' For validating the Floating Point Numbers
' MODULE
Public Sub ValidateDel(txtnum As TextBox, ByVal m_Precision As Integer, KeyCode As Integer)

  Dim m_NumBeforeDot As Integer, m_NumAfterDot As Integer
  Dim TempInt As Integer

  If KeyCode = vbKeyDelete Then
    If m_Precision > 0 Then
      TempInt = InStr(txtnum, ".")
      If TempInt > 0 Then
        m_NumBeforeDot = TempInt - 1
        m_NumAfterDot = Len(txtnum) - TempInt
      Else
        m_NumBeforeDot = Len(Trim(txtnum))
        m_NumAfterDot = 0
        TempInt = txtnum.MaxLength - m_Precision
      End If

      If (txtnum.SelStart = TempInt - 1) Then
        If m_NumBeforeDot + m_NumAfterDot >= txtnum.MaxLength - m_Precision Then
          KeyCode = 0
        End If
      End If
    End If
  End If
End Sub

Public Sub ValidateNum(txtnum As TextBox, ByVal m_Precision As Integer, KeyAscii As Integer)

  Dim m_NumBeforeDot As Integer, m_NumAfterDot As Integer
  Dim TempInt As Integer

  If (KeyAscii <> vbKeyReturn) And _
    ((KeyAscii < vbKey0) Or (KeyAscii > vbKey9)) And _
    (KeyAscii <> vbKeyBack) Then

    If KeyAscii = 46 Then ' Dot.
      If m_Precision = 0 Then
        KeyAscii = 0
        Exit Sub
      Else
        If InStr(txtnum, ".") > 0 Then
          KeyAscii = 0

          Exit Sub
        End If
      End If
    Else
      KeyAscii = 0
      Exit Sub
    End If

  End If

  If KeyAscii = 0 Then Exit Sub

  If m_Precision > 0 Then
     TempInt = InStr(txtnum, ".")
     If TempInt > 0 Then
       m_NumBeforeDot = TempInt - 1
       m_NumAfterDot = Len(txtnum) - TempInt
     Else
       m_NumBeforeDot = Len(txtnum)
       If txtnum.SelStart < m_NumBeforeDot - m_Precision Then
         KeyAscii = 0
         Exit Sub
       End If
       m_NumAfterDot = 0
       TempInt = txtnum.MaxLength - m_Precision
     End If

     If KeyAscii >= vbKey0 And KeyAscii <= vbKey9 Then
       If Not (((m_NumBeforeDot < txtnum.MaxLength - m_Precision - 1) _
         And (txtnum.SelStart < TempInt)) Or _
         ((m_NumAfterDot < m_Precision) And (txtnum.SelStart >= TempInt))) Then

         KeyAscii = 0

       End If
     ElseIf (KeyAscii = vbKeyBack) And (txtnum.SelStart = TempInt) Then
         If m_NumBeforeDot + m_NumAfterDot >= txtnum.MaxLength - m_Precision Then
           KeyAscii = 0
         End If
     End If
   End If
End Sub