Directory.GetFiles() in Modified Date/Time Order Pt2

Following on from this. I've noticed that it only gives you to the second accuracy. If your software is capable of making more than one file per second, the sort order will be date/time to the second then alphanumerically on the filename. Not ideal if your filenames are guids, the following class gives date/time sort accuracy of 100 nanosecond intervals then alphanumerically on filename :-

   1:  Imports System.IO

   2:  Imports System.Runtime.InteropServices

   3:  Imports System.Runtime.InteropServices.ComTypes

   4:  Imports Microsoft.Win32.SafeHandles

   5:  Imports Microsoft.Win32

   6:  Public Class clsCompareFileInfo

   7:      Implements IComparer

8:

   9:      Private Const GENERIC_READ = &H80000000

  10:      Private Const OPEN_EXISTING = 3

  11:      Private Const FILE_SHARE_READ = &H1

  12:      Private Const FILE_SHARE_WRITE = &H2

  13:      Private Const FILE_ATTRIBUTE_NORMAL = &H80

  14:      Private Const FILE_FLAG_NO_BUFFERING = &H20000000

15:

  16:      Public Structure FILETIME

  17:          Public dwLowDateTime As Long

  18:          Public dwHighDateTime As Long

  19:      End Structure

20:

  21:      Private Declare Function GetFileTime Lib "kernel32" (ByVal hFile As Integer, ByRef lpCreationTime As ComTypes.FILETIME, ByRef lpLastAccessTime As ComTypes.FILETIME, ByRef lpLastWriteTime As ComTypes.FILETIME) As Integer

22:

  23:      Private Declare Auto Function CreateFile Lib "kernel32.dll" (ByVal lpFileName As String, _

  24:  ByVal dwDesiredAccess As Integer, ByVal dwShareMode As Integer, _

  25:  ByVal lpSecurityAttributes As IntPtr, ByVal dwCreationDisposition As Integer, _

  26:  ByVal dwFlagsAndAttributes As Integer, ByVal hTemplateFile As IntPtr) As IntPtr

27:

  28:      Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

  29:      <DllImport( _

  30:                  "kernel32.dll", _

  31:                  CharSet:=CharSet.Auto, _

  32:                  SetLastError:=True)> _

  33:              Friend Shared Function CompareFileTime( _

  34:              ByRef lpFileTime1 As ComTypes.FILETIME, _

  35:              ByRef lpFileTime2 As ComTypes.FILETIME) _

  36:              As Integer

  37:      End Function

38:

  39:      Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare

  40:          Dim File1 As FileInfo

  41:          Dim File2 As FileInfo

42:

  43:          File1 = DirectCast(x, FileInfo)

  44:          File2 = DirectCast(y, FileInfo)

45:

  46:          Dim x_Created As ComTypes.FILETIME

  47:          Dim x_Modified As ComTypes.FILETIME

  48:          Dim x_Accessed As ComTypes.FILETIME

  49:          Dim y_Created As ComTypes.FILETIME

  50:          Dim y_Modified As ComTypes.FILETIME

  51:          Dim y_Accessed As ComTypes.FILETIME

52:

  53:          Dim fhandle As IntPtr = CreateFile(File1.FullName, GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero)

  54:          GetFileTime(fhandle, x_Created, x_Accessed, x_Modified)

55:

  56:          Dim fhandle2 As IntPtr = CreateFile(File2.FullName, GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero)

  57:          GetFileTime(fhandle2, y_Created, y_Accessed, y_Modified)

58:

  59:          CloseHandle(fhandle)

  60:          CloseHandle(fhandle2)

61:

  62:          Compare = CompareFileTime(x_Modified, y_Modified)

  63:      End Function

  64:  End Class

Posted on Thursday, July 10, 2008 9:19 PM | Back to top