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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

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