VBA - Trim function : reduce time of operation / freezing - vba

Question

I have written code in VBA that removes some potential spaces between characters. The code works pretty well but becomes really slow when the file contains thousands of rows. I'd like to know if it's possible to improve it, in order to reduce the time of operation, but also mainly to stop the file from freezing. Here is the code:
Sub Test()
Dim cell as Range
Dim sht As Worksheet
Dim LastRow As Long
Dim StartCell As Range
Dim areaToTrim As Range
Set sht = ThisWorkbook.Worksheets("SS upload")
Set StartCell = sht.Range("A14")
LastRow = sht.Cells(sht.Rows.Count, StartCell.Column).End(xlUp).Row
Set areaToTrim = sht.Range("B14:B" & LastRow)
For Each cell In areaToTrim
cell.Value = Trim(cell.Value)
Next cell
End Sub

Answer 1

The fastest way is to read the range into an array, trim it there and then write it back to the range:
Sub Test()
Dim sht As Worksheet
Dim LastRow As Long
Dim StartCell As Range
Dim areaToTrim As Range
Dim varArray() As Variant
Dim i As Long
Set sht = ThisWorkbook.Worksheets("SS upload")
Set StartCell = sht.Range("A14")
LastRow = sht.Cells(sht.Rows.Count, StartCell.Column).End(xlUp).Row
Set areaToTrim = sht.Range("B14:B" & LastRow)
varArray = areaToTrim ' Read range into array
For i = LBound(varArray, 1) To UBound(varArray, 1)
varArray(i, 1) = Trim(varArray(i, 1))
Next i
areaToTrim.Value = varArray ' Write array back to range
End Sub
No need to worry about Application.ScreenUpdating or Application.Calculation. Nice and simple!
If you are still worried about any responsiveness, put a DoEventsin the body of the loop.

Answer 2

You can prevent the freezing when you insert DoEvents in your loop.
And then execute it, say every hundredth time.
This will make the loop run a little slower, but allows the user to use the GUI meanwhile.
...
Dim cnt As Integer
For Each cell In areaToTrim
cell.Value = Trim(cell.Value)
cnt=cnt + 1
If cnt Mod 100 = 0 Then
DoEvents
End If
Next cell
...
You can play around with the number to optimize it for your needs.
DoEvents brings also some problems with it. A good explanation about DoEvents can be found here.

Answer 3

Try like this, to reduce screenupdating. This is a piece of code, that I always use, thus some of the commands are probably a bit too much for the current question, but they can be still useful.
As a second point - do not declare a variable with the name Cell, you can suffer a bit from this later. Declare it rngCell or myCell or anything else, which is not part of the VBE variables.
Public Sub TestMe()
Call OnStart
'YourCode
Call OnEnd
End Sub
Public Sub OnEnd()
Application.ScreenUpdating = True
Application.EnableEvents = True
Application.AskToUpdateLinks = True
Application.DisplayAlerts = True
Application.Calculation = xlAutomatic
ThisWorkbook.Date1904 = False
Application.StatusBar = False
End Sub
Public Sub OnStart()
Application.ScreenUpdating = False
Application.EnableEvents = False
Application.AskToUpdateLinks = False
Application.DisplayAlerts = False
Application.Calculation = xlAutomatic
ThisWorkbook.Date1904 = False
ActiveWindow.View = xlNormalView
End Sub
If you feel like it, you may save the range as an array and do the trim operation there. However, it may overcomplicate your code, if you are not used to work with arrays - Trim Cells using VBA in Excel