Introduction:
This macro can be used to count how many files exist in a folder and, if passed the file extension, can also be used to count only files of a specific type. (For example "xls" files.) I've actually published two articles along this vein at [url="http://www.vbaexpress.com"]VBA Expresss[/url], but this one uses the File System Object (some know it as the File Scripting Object, or just FSO,) to do it. The biggest reason for the re-write is that I needed to use this in an Excel 2007 instance, which does not support the FileSearch method.

If you are looking for a version to count the files in a folder AND subfolders, then look here.

Macro Purpose:

1. Count all files in a folder
2. Count all files of a specific type in a folder

Examples of where this function shines:

1. When checking if you should process a folder for any reason, this can be used to quickly test if any files worth looking at exist inside.

Macro Weakness(es):

1. None known.

Versions Tested:
This function has been tested with Excel 2007. Due to the use of the InStrRev function, it will not work in Excel 97. While I have not tested it with Excel 2000 and Excel 2002 (XP) without any modifications, I don't expect any issues with it. (If you find one, let me know.)

VBA Code Required:

1. Place the following code in a standard module of the workbook you wish to use it in.

Private Function CountFiles(strDirectory As String, Optional strExt As String = "*.*") As Double
'Author          : Ken Puls (www.excelguru.ca)
'Function purpose: To count files in a directory.  If a file extension is provided,
'   then count only files of that type, otherwise return a count of all files.

    Dim objFso As Object
    Dim objFiles As Object
    Dim objFile As Object

    'Set Error Handling
    On Error GoTo EarlyExit

    'Create objects to get a count of files in the directory
    Set objFso = CreateObject("Scripting.FileSystemObject")
    Set objFiles = objFso.GetFolder(strDirectory).Files

    'Count files (that match the extension if provided)
    If strExt = "*.*" Then
        CountFiles = objFiles.Count
    Else
        For Each objFile In objFiles
            If UCase(Right(objFile.Path, (Len(objFile.Path) - InStrRev(objFile.Path, ".")))) = UCase(strExt) Then
                CountFiles = CountFiles + 1
            End If
        Next objFile
    End If

EarlyExit:
    'Clean up
    On Error Resume Next
    Set objFile = Nothing
    Set objFiles = Nothing
    Set objFso = Nothing
    On Error GoTo 0

End Function

How to use the code:

1. Call it from another routine, as shown using a FileDialog example below. (FileDialogFolderPicker may not work in Excel 2000.)
2. Please note that you should provide the full file path to the folder as the argument.
3. You may supply or ignore the trailing \ on a directory if you choose. It will work either way.

Sub Test()
'Author       : Ken Puls (www.excelguru.ca)
'Macro Purpose: Test the CountFiles function

    Dim flDlg As FileDialog
    Dim dblCount As Double

    Set flDlg = Application.FileDialog(msoFileDialogFolderPicker)
    flDlg.Show
    dblCount = CountFiles(flDlg.SelectedItems(1))
    Debug.Print dblCount
End Sub

References:
More about the File System Object can be found here on MSDN.

As mentioned above, this routine is based off works that I originally submitted as KB entries at VBAExpress. Those entries are:
Count Files in a directory (All file types only, using FileScriptingObject)
Count Files in a directory (All file types or one specific type only, using FileSearch)