Too many iterations in loop - vbscript

Question

This script collects all files in a folder and renames the files by appending the number of lines to the file name. All files are .txt files. The method (since fso.MoveFile and fso.DeleteFile are too particular, generating permissions errors) is to
create the text files,
then create a collection of the files in the folder,
then copy each file into the same folder with a new name, and
finally to delete the original file that was copied.
The script works ok, unless there are no empty text files in the collection. What happens is, the collection gets rebuilt with the new files and the script once again renames the files. I know I can prevent this by checking each file for the existence of certain repeating character strings, but I'd like to know what's happening? Why does the script rebuild the file collection and run through them again renaming each one? This continues on until I kill the process.
Another interesting factoid is, if I happen to trap an empty text file, my message is displayed and the script stops there, but has still reprocessed the first file in the collection a second time. Note that the empty file just happens to be the last one in the collection, but the first filed is once again processed.
So, by design a created text file named 'ab0.txt' gets renamed to 'ab0-15.txt' since it has 15 lines of text in it. What happens is this newly renamed file looks like 'ab0-15-15-15-15-15-15-15-15-15-15.txt'
Questions: What's going on? And is there a better and more efficient way to accomplish this objective?
Here's the code pertinent to the issue:
Set fso = CreateObject("Scripting.FileSystemObject")
Set oFolder = fso.GetFolder(strSaveTo)
Set colFiles = oFolder.Files
' Call Sub to copy and rename
ChangeFileName colFiles
MsgBox("File renaming complete.")
' Exit code
Sub ChangeFileName(collectionSet)
Const ForReading = 1
Dim oFile
For Each oFile In collectionSet
Set LineCnt = fso.OpenTextFile(oFile, ForReading)
If oFile.Size = 0 then
'if this msg is not included, weird things happen
MsgBox("The file named " & oFile & _
" is empty.You may want to verify and manually delete it.")
'[I had some code in here to delete the empty file, but nothing worked]
Else
Do While LineCnt.AtEndOfStream <> True
LineCnt.SkipLine
Loop
lineVar = lineCnt.Line-1
strNewFile = strSaveTo & Left(oFile.name, Len(oFile.name)-4) & _
"-" & lineVar & ".txt"
fso.CopyFile oFile, strNewFile
LineCnt.Close
fso.DeleteFile oFile, True
End If
Next
End Sub

Answer 1

I've heard anecdotal evidence that the Files collection is "live", meaning that newly created files will be added to the collection and iterated over, but I can't find any documentation that says one way or the other. In any case, it's probably a good idea to copy the File objects in the collection to an array first before processing them:
Dim oFile
Dim fileArray()
Dim i
ReDim fileArray(collectionSet - 1)
i = 0
For Each oFile in collectionSet
Set fileArray(i) = oFile
i = i + 1
Next
For Each oFile In fileArray
' Count lines and rename
Next

Answer 2

It seems that collectionSet is the collection of files in the folder that you are trying to modify. The problem is that with each pass through the for-each loop you are adding files to this folder, some of which are fed back into the loop. What you need to do is the find a way to take a snapshot of the folder before you try to iterate over it. The way to do this would be to replace the folder collectionSet by a collection of strings which are the names of the files before you iterate over it, and modify your code to open the files by their name (instead of via a file object). That way the collection won't be expanding while you iterate over it.

Answer 3

You should create your vars in the scope they are used (e.g. your
file/folder objects are used in the sub.
Always explicit(ly) declare your vars.
You don't need to copy the file and rename it then do the delete.
Just rename it with the FileObject.Name property.
Here is an example:
Option Explicit 'always declare your vars!
Dim strFolder: strFolder = "c:\temp\Rename Test"
Dim strExtension: strExtension = "txt"
' Call Sub to rename the files in the folder
ChangeFileName strFolder, strExtension
Sub ChangeFileName(strFolder, strExtension)
Const ForReading = 1
Dim FSO: set FSO = CreateObject("Scripting.FileSystemObject")
Dim objFolder: set objFolder = FSO.GetFolder(strFolder)
Dim colFiles: set colFiles = objFolder.Files
Dim objFile
Dim intCount
Dim strFileName
Dim objTextStream
For Each objFile In colFiles
msgbox "File: " & objfile.path & vbcrlf & FSO.GetExtensionName(objFile.path)
if UCase(FSO.GetExtensionName(objFile.Path)) = UCase(strExtension) and _
objFile.Size > 0 then
'set LineCnt = FSO.OpenTextFile(objFile, ForReading)
set objTextStream = objFile.OpenAsTextStream(ForReading,-2)
intCount = 0
strFileName = objFile.Name
Do While objTextStream.AtEndOfStream <> True
intCount = intCount + 1
objTextStream.ReadLine
Loop
objTextStream.Close
objFile.Name = FSO.GetBaseName(objFile.Path) & "-" & _
intCount & "." & FSO.GetExtensionName(objFile.Path)
end if
Next
End Sub