Checking Excel 2003 data validation - excel

Question

The following bit of VBA will highlight any cells in a sheet with data validation errors:
Sub CheckValidation(sht As Worksheet)
Dim cell As Range
Dim rngDV As Range
Dim dvError As Boolean
On Error Resume Next
Set rngDV = sht.UsedRange.SpecialCells(xlCellTypeAllValidation)
On Error GoTo 0
If rngDV Is Nothing Then
sht.ClearCircles
Else
dvError = False
For Each cell In rngDV
If Not cell.Validation.Value Then
dvError = True
Exit For
End If
Next
If dvError Then
sht.CircleInvalid
sht.Activate
Else
sht.ClearCircles
End If
End If
End Sub
However, the "For Each" loop runs really slowly in sheets with a lot of data validation.
Does anyone know of a way to avoid the "For Each" loop, or speed it up somehow?
I would have thought that the following would be equivalent to set the value of 'dvError':
dvError = Not rngDV.Validation.Value
But for some reason, rngDV.Validation.Value is true even when there are data validation errors.

Answer 1

I had a slightly different requirement where I wanted to restrict the values entered by a user to a valid date range or the text "ASAP" which I resolved using the following;
Private Sub Worksheet_Change(ByVal Target As Range)
Dim sErr As String
Dim sProc As String
On Error GoTo ErrHandler
Application.EnableEvents = False
Select Case Target.Column
Case 11
sProc = "Validate Date"
'The value must be a date between "1 Nov 2011" and "30 Jun 2012" or "ASAP"...
If IsDate(Target.Value) Then
If Target.Value < CDate("2011-11-01") _
Or Target.Value > CDate("2012-06-30") Then
Err.Raise vbObjectError + 1
End If
ElseIf LCase(Target.Value) = "asap" Then
Target.Value = "ASAP"
ElseIf Len(Trim(Target.Value)) = 0 Then
Target.Value = vbNullString
Else
Err.Raise vbObjectError + 1
End If
End Select
ErrHandler:
Select Case Err.Number
Case 0
'Nothing to do...
Case vbObjectError + 1
sErr = "The Date must be between ""1 Nov 2011"" and ""30 Jun 2012"" or equal ""ASAP""."
Case Else
sErr = Err.Description
End Select
If Len(Trim(sErr)) > 0 Then
Target.Select
MsgBox sErr, vbInformation + vbOKOnly, sProc
Target.Value = vbNullString
End If
Application.EnableEvents = True
End Sub

Answer 2

Tried your code and it's working quite fast with 4536 cells containing validations - as you are rightly breaking your FOR at the first occurence of an unvalidated cell
I tried to measure time at various points of your code by following:
Dim Tick As Variant
Tick = Now()
' ... code
Debug.Print "ValCount", rngDV.Cells.Count ' just to see how many cells are in that range
' ... code
Debug.Print "Pt1", (Now() - Tick) * 86400000 'display milliseconds
' ... code
Debug.Print "Pt2", (Now() - Tick) * 86400000 'display milliseconds
' ... code
Debug.Print "Pt3", (Now() - Tick) * 86400000 'display milliseconds
' etc.
and got a not measureable delay (except when stepping thru debugger with F8 - of course)
As a generic hint ... try to find out where exactly your code is slow and let's take it from there.