Unable to get missingFiles.txt to add values - regex

Question

I've been working on this for awhile and have gotten lots of help (Thank you!). I believe I'm on the last step of my code. I need to write to a MissingFiles.txt file, I've added it in my Else clause but it never fires. Even when I know there are missing graphics. It does copy the files found in a try/catch. I was thinking maybe add the missingText file code in the catch part but that didn't do anything.
So I'm back to using the Else clause in my If System.IO.File.exists else part.
Private Sub btnMoveGraphics(sender As Object, e As EventArgs)
Dim imgLocation = txtSearchICN.Text
Dim MissingFiles = MoveLocation & "\Reports\MissingGraphicList.txt"
Dim fileNames = System.IO.Directory.GetFiles(imgLocation).Join(
GraphicList,
Function(p) Path.GetFileNameWithoutExtension(p),
Function(f) f,
Function(p, f) p)
' create the directory first (does nothing if it already exists)
Dim MoveImgTo = MovePath & "\Figures"
Directory.CreateDirectory(MoveImgTo)
' copy each file
For Each fileName In fileNames
Dim copyFilesTo = Path.Combine(MoveImgTo, Path.GetFileName(fileName))
If System.IO.File.Exists(fileName) Then
'The file exists
Debug.Write(vbCr & "ICN file name - " & fileName)
Try
System.IO.File.Copy(fileName, Path.Combine(MoveImgTo, Path.GetFileName(fileName)))
Catch ex As Exception
End Try
Else
Debug.Write(vbCr & "Missing file name - " & fileName)
'the file doesn't exist
Dim objWriter As New System.IO.StreamWriter(MissingFiles, IO.FileMode.Append)
objWriter.WriteLine(fileName)
objWriter.Close()
End If
Next
End Sub

Answer 1

There are several possible solutions to your question. They all involve two steps, (1) get the list of files in the imgLocation folder, and (2) compare that list with the GraphicList list.
One solution is to compare the two lists directly.
' Get the list of file
Dim fileNames as String() = System.IO.Directory.GetFiles(imgLocation)
' For each name in GraphicList, we want to check whether it is in fileNames.
For Each name As String In GraphicList
' See whether name appears in fileNames.
Dim found As Boolean = False
' Search name in fileNames.
For Each fileName As String In fileNames
' GraphicList consists of filename without extension, so we compare name
' with the filename without its extension.
If Path.GetFileNameWithoutExtension(fileName) = name Then
' The fileName name exists.
' ... do whatever code ...
' Set found to True so we do not process name as missing, and exit For.
found = True
Exit For
End If
Next
If Not found = True Then
' There is no fileName name.
' ... do whatever code ...
End If
Next
If the number of files you have are in the hundreds, then this solution will be efficient enough. However, if you have many more files, in the thousands or more, then there are more efficient solutions that involves using data structures such as dictionaries and sets.
Final note, instead of:
Dim objWriter As New System.IO.StreamWriter(MissingFiles, IO.FileMode.Append)
objWriter.WriteLine(fileName) ' <== Here it should be a name from GraphicFile because filename does not exist.
objWriter.Close()
You could simply write:
File.AppendAllText(MissingFiles, name & vbNewLine)