Loop through folder names on a server directory

Question

I have the following code to loop through a directory of folders and print all folders names with their paths in a worksheet. This is a follow up question to this one: Excel VBA - Get Folder Names Looking for code optimization for faster and better performance.

Sub PrintFolders()
 Dim wb As Workbook
 Dim ws As Worksheet
 Dim objFSO As Object
 Dim objFolder As Object
 Dim objSubFolder As Object
 Dim i As Integer
 Dim Folder_Name As String
 Application.ScreenUpdating = False
 Application.Calculation = xlCalculationManual
 Application.StatusBar = ""
 Set wb = ThisWorkbook
 Set wsControl = wb.Sheets("Control"): Set wsOutput = wb.Sheets("Output")
 Folder_Name = wsControl.Cells(1, 2)
 If Folder_Name = "" Then
 MsgBox "Path location is not entered. Please enter path"
 wsControl.Cells(1, 2).Select
 End
 End If
 Set objFSO = CreateObject("Scripting.FileSystemObject")
 Set objFolder = objFSO.GetFolder(Folder_Name)
 i = 1
 Dim MyArr() As Variant
 ReDim MyArr(1 To i, 1 To 2)
 On Error GoTo CleanFail
 Application.EnableCancelKey = xlErrorHandler
 Const IterationsToUpdate As Integer = 10
 For Each objSubFolder In objFolder.subfolders
 MyArr(i, 1) = objSubFolder.Name
 MyArr(i, 2) = objSubFolder.Path
 i = i + 1
 MyArr = Application.Transpose(MyArr)
 ReDim Preserve MyArr(1 To 2, 1 To i)
 MyArr = Application.Transpose(MyArr)
 If i Mod IterationsToUpdate = 0 Then
 Application.StatusBar = objSubFolder.Path & " " & objSubFolder.Name
 DoEvents
 End If
 Next objSubFolder
 Application.StatusBar = ""
 wsOutput.Rows("2:1048576").Delete
 Dim Destination As Range
 Set Destination = wsOutput.Range("A2")
 Destination.Resize(UBound(MyArr, 1), UBound(MyArr, 2)).Value = MyArr
 wsOutput.Columns.EntireColumn.AutoFit: wsOutput.UsedRange.HorizontalAlignment = xlCenter
 wsOutput.Activate
 MsgBox ("Done")
 CleanExit:
 Application.StatusBar = False
 Application.StatusBar = ""
 Application.Cursor = xlDefault
 Application.ScreenUpdating = True
 Application.Calculation = xlCalculationAutomatic
 Exit Sub
 CleanFail:
 Const MsgTitle As String = "Operation not completed"
 If Err.Number = 18 Then
 MsgBox "Operation was cancelled.", vbInformation, MsgTitle
 Else
 MsgBox "An error has occurred: " & Err.Description, vbCritical, MsgTitle
 End If
 Resume CleanExit
End Sub

• Mathieu Guindon: Awesome, welcome back! I suggest you edit this post to include a bit more context and a link to your previous post, as this is a follow-up question.

Answer 1

Performance

If you really want to squeeze out every ounce of performance, I recommend early binding the FileSystemObject and related classes. From the "What form of binding should I use" from this MSDN article:

Early binding is the preferred method. It is the best performer because your application binds directly to the address of the function being called and there is no extra overhead in doing a run-time lookup. In terms of overall execution speed, it is at least twice as fast as late binding.

Beyond that, there's not much more you can do in the way of performance. Most of the time here is going to talking to the remote file system. You could remove the ability to cancel or not update the status bar, but it's my belief the UX would suffer too much.

One thing you could do though is alter how often you update the status bar based on how many subfolders are found. Instead of having IterationsToUpdate be a constant, make it a variable and figure out a way to calculate how often the status bar should be updated using the SubFolder's Count property. Perhaps update at each 5%.

 IterationsToUpdate = CInt(Subfolders.Count * 0.05)

---

Update:

I changed my mind. There is something more you can do to make the performance better. Several things actually, but I'll let you decide if the second one is really worth it or not.

1. Stop Re-dimensioning the array. You already know how big it should be, so Dim it once and only once.

   Dim MyArr(1 To objFolder.Subfolders.Count, 1 To 2) As Variant
   

   This removes a lot of overhead inside of the loop. When you ReDim Preserve, you're effectively making a copy of the array at each iteration. There's no reason to do this when you know how big the array should be up front.

(削除) 2. You could unroll the loop. Be aware, that doing this will cause a maintenance headache, but it *could significantly speed up the loop through the subfolders. This works by setting multiple "positions" of your array during each iteration.

*I do mean could. There's no way of knowing if it will actually perform better or not until it is tried and benchmarked. (削除ここまで)

Unfortunately, you can't access items in the Folders collection by integral index, only by key, so unrolling the loop is not an option.

---

Misc

• Why delete the entire range here? Are all of those rows always filled? Could there ever be more?

  wsOutput.Rows("2:1048576").Delete
  

  It would be better to find the last non-empty row.

• Why are you activating here? Smells like an unintended side effect to me.

   wsOutput.Activate
  

  Perhaps you meant to select the range for the user? If so, the correct way to do that is this.

   wsOutput.Select
  

• You don't need parenthesis here.

  MsgBox ("Done")
  

  You're wasting at least a few cycles telling the runtime to evaluate the default property of... a literal. I recommend reading over this StackOverflow Q & A that details the rules about using parenthesis in a routine call for more information.

  It would also be nice to display the "Information" icon on the message box. It's a nicer UX.

   MsgBox "Done", vbInformation
  

• Consider using another constant here instead of the literal 18.

  If Err.Number = 18 Then
  

  It's pretty clear what's going on from the context, but if I want to know exactly what that error is, I'd have to look it up. A (well named) constant keeps the maintainer in the IDE as it removes any ambiguity.

• RubberDuck: I added an update. I found another performance optimization.
• Anurag Singh: @RubberDuck.Thanks for the update, although VBA won't be let me Dim an array with a variable. Dim MyArr(1 To objFolder.Subfolders.Count, 1 To 2) As Variant. Instead I had to do this to make it work Dim MyArr() As Variant ReDim MyArr(1 To objFolder.SubFolders.Count, 1 To 2) As Variant
• RubberDuck: Sorry about that. I'm also sorry I couldn't help more. I was really trying to figure out how to speed this up.
• Anurag Singh: No need to be sorry you have helped enough, this works wonderfully well and I learnt so much with this code. Cheers!!