Measure the Size of a Huge File

[Ellis Dee]

Here's the FileSize() method in my XP library, which of course handles files >2gig. (As do all the drive size methods, obviously.) I'm not going to bother adding in hungarian notation, which I do not use in the XP library to make the interface more intuitive.

Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Any, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function GetFileSize Lib "kernel32" (ByVal hFile As Long, lpFileSizeHigh As Long) As Long
 
' Currency handles file sizes over 2 gig
' Thanks to Richard Newcombe from codeguru.com
Public Function GetSize(ByVal File As String) As Currency
    Const GENERIC_READ = &H80000000
    Const FILE_SHARE_READ = &H1
    Const FILE_SHARE_WRITE = &H2
    Const OPEN_EXISTING = 3
    Dim lngHandle As Long
    Dim lngLow As Long
    Dim lngHigh As Long
    Dim curFileSize As Currency
    
    ' Open the file
    lngHandle = CreateFile(File, GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, 0&, OPEN_EXISTING, 0, 0)
    ' Get the file size
    lngLow = GetFileSize(lngHandle, lngHigh)
    CloseHandle lngHandle
    ' Combine the Low and High values into one currency
    ' Must use the '@' currency declaration or IDE will balk
    curFileSize = 4294967295@ * lngHigh
    If lngLow < 0 Then
        curFileSize = curFileSize + (4294967295@ + (lngLow + 1))
    Else
        curFileSize = curFileSize + lngLow
    End If
    GetSize = curFileSize
End Function

This is about as fast and easy as it gets.