Excel VBA efficient get file names function

Question

I need to get a collection of file names from a folder on a remote server using VBA in excel 2010. I have a function that works and in the majority of cases it would do the

Answer 1

Ok, I have found a solution that works for my situation and perhaps others will find it useful too. This soution uses the windows API and gets me the filenames in 1 second or less where as the FSO method was taking several minutes. It still involves a loop so i'm not certain why it is so much faster but it is.

This takes a path like "c:\windows\" and returns a collection of all the files (and directories) in that folder. The exact parameters I have used require windows 7 or newer, see the comments in the declarations.

'for windows API call to FindFirstFileEx
Private Const INVALID_HANDLE_VALUE = -1
Private Const MAX_PATH = 260

Private Type FILETIME
    dwLowDateTime   As Long
    dwHighDateTime  As Long
End Type

Private Type WIN32_FIND_DATA
    dwFileAttributes    As Long
    ftCreationTime      As FILETIME
    ftLastAccessTime    As FILETIME
    ftLastWriteTime     As FILETIME
    nFileSizeHigh       As Long
    nFileSizeLow        As Long
    dwReserved0         As Long
    dwReserved1         As Long
    cFileName           As String * MAX_PATH
    cAlternate          As String * 14
End Type

Private Const FIND_FIRST_EX_CASE_SENSITIVE  As Long = 1
'MSDN: "This value is not supported until Windows Server 2008 R2 and Windows 7."
Private Const FIND_FIRST_EX_LARGE_FETCH     As Long = 2

Private Enum FINDEX_SEARCH_OPS
    FindExSearchNameMatch
    FindExSearchLimitToDirectories
    FindExSearchLimitToDevices
End Enum

Private Enum FINDEX_INFO_LEVELS
    FindExInfoStandard
    FindExInfoBasic 'MSDN: "This value is not supported until Windows Server 2008 R2 and Windows 7."
    FindExInfoMaxInfoLevel
End Enum

Private Declare Function FindFirstFileEx Lib "kernel32" Alias "FindFirstFileExA" ( _
ByVal lpFileName As String, ByVal fInfoLevelId As Long, lpFindFileData As WIN32_FIND_DATA, _
    ByVal fSearchOp As Long, ByVal lpSearchFilter As Long, ByVal dwAdditionalFlags As Long) As Long
Private Declare Function FindNextFile Lib "kernel32" Alias "FindNextFileA" ( _
    ByVal hFindFile As Long, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function FindClose Lib "kernel32" (ByVal hFindFile As Long) As Long


Private Function GetFiles(ByVal sPath As String) As Collection

    Dim fileInfo    As WIN32_FIND_DATA  'buffer for file info
    Dim hFile       As Long             'file handle
    Dim colFiles    As New Collection

    sPath = sPath & "*.*"

    hFile = FindFirstFileEx(sPath & vbNullChar, FindExInfoBasic, fileInfo, FindExSearchNameMatch, 0&, FIND_FIRST_EX_LARGE_FETCH)

    If hFile <> INVALID_HANDLE_VALUE Then
        Do While FindNextFile(hFile, fileInfo)
            colFiles.Add Left(fileInfo.cFileName, InStr(fileInfo.cFileName, vbNullChar) - 1)
        Loop

        FindClose hFile
    End If

    Set GetFiles = colFiles

End Function