will FileLen give an error on very large files?
in [Visual Basic]
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From: Ian Williams on 18 Nov 2009 09:51 RB Smissaert wrote: > Hi Olaf, > > Had a better look now and yes, this knocks a few more percent off, more > so when testing on a large file. > This is the function I will be using then and thanks for the tip. > > Function FileSizeAPI(strFilePath As String) As Currency > > Dim hFind As Long > Dim WFD As WIN32_FIND_DATA > > hFind = FindFirstFile(StrPtr(strFilePath), WFD) > > If hFind = -1& Then > FileSizeAPI = -1@ > Else > FindClose hFind > If (WFD.nFileSizeHigh = 0&) And (WFD.nFileSizeLow > 0&) Then > FileSizeAPI = WFD.nFileSizeLow > Else > WFD.dwReserved0 = WFD.nFileSizeHigh > CopyMemory FileSizeAPI2, WFD.nFileSizeLow, 8 > FileSizeAPI = FileSizeAPI2 * 10000@ > End If > End If > > End Function > > > RBS <snip> Here's a slighter simpler version, no CopyMemory involved and no redundant checking on the nFileSizeHigh value Public Const INVALID_HANDLE_VALUE = -1 Public Const MAXDWORD = 4294967296# Function FileSizeApi(ByVal FilePath As String) As Currency Dim hFile As Long Dim wfd As WIN32_FIND_DATA hFile = FindFirstFile(FilePath, wfd) If hFile <> INVALID_HANDLE_VALUE Then FindClose hFile With wfd FileSizeApi = CCur(.nFileSizeHigh) * MAXDWORD + nFileSizeLow End With Else FileSizeApi = -1 End If End Function Ian
From: Nobody on 18 Nov 2009 10:13 "Ian Williams" <ian(a)kingsoft-dk.com> wrote in message news:ubufu6FaKHA.4688(a)TK2MSFTNGP06.phx.gbl... > Here's a slighter simpler version, no CopyMemory involved and no redundant > checking on the nFileSizeHigh value > > Public Const INVALID_HANDLE_VALUE = -1 > Public Const MAXDWORD = 4294967296# > > Function FileSizeApi(ByVal FilePath As String) As Currency > Dim hFile As Long > Dim wfd As WIN32_FIND_DATA > hFile = FindFirstFile(FilePath, wfd) > If hFile <> INVALID_HANDLE_VALUE Then > FindClose hFile > With wfd > FileSizeApi = CCur(.nFileSizeHigh) * MAXDWORD + nFileSizeLow > End With > Else > FileSizeApi = -1 > End If > End Function Unfortunately, CConvert functions seem to be implemented in VB6 as function calls. I have seen the assembly output for some of them(From memory CLng), not CCur in particular. However, I believe that you can do what you want if you declare the constant As Currency. Example: Public Const MAXDWORD = 4294967296@ Or Public Const MAXDWORD As Currency = 4294967296@ Then: FileSizeApi = MAXDWORD * .nFileSizeHigh + .nFileSizeLow
From: Bob Butler on 18 Nov 2009 10:14 "Ian Williams" <ian(a)kingsoft-dk.com> wrote in message news:ubufu6FaKHA.4688(a)TK2MSFTNGP06.phx.gbl... > RB Smissaert wrote: <cut> >> If (WFD.nFileSizeHigh = 0&) And (WFD.nFileSizeLow > 0&) Then >> FileSizeAPI = WFD.nFileSizeLow <cut> > FileSizeApi = CCur(.nFileSizeHigh) * MAXDWORD + nFileSizeLow If the file size is between &H80000000 and &HFFFFFFFF then won't nFileSizeLow be a negative value?
From: Ian Williams on 18 Nov 2009 10:32 Nobody wrote: < > Unfortunately, CConvert functions seem to be implemented in VB6 as function > calls. I have seen the assembly output for some of them(From memory CLng), > not CCur in particular. However, I believe that you can do what you want if > you declare the constant As Currency. Example: > > Public Const MAXDWORD = 4294967296@ > > Or > > Public Const MAXDWORD As Currency = 4294967296@ > > Then: > > FileSizeApi = MAXDWORD * .nFileSizeHigh + .nFileSizeLow > > > It was the IDE that changed the type declaration to Double. I've also spotted that the function messes up when checking a file which is between 2GB & 4GB - you get a negative result, so here's one that works. Ian Public Const MAXDWORD As Currency = 4294967296@ Function FileSizeApi(ByVal FilePath As String) As Currency Dim hFile As Long Dim wfd As WIN32_FIND_DATA hFile = FindFirstFile(FilePath, wfd) If hFile <> INVALID_HANDLE_VALUE Then FindClose hFile With wfd If .nFileSizeLow < 0 Then FileSizeApi = MAXDWORD + .nFileSizeLow Else FileSizeApi = .nFileSizeLow End If FileSizeApi = MAXDWORD * .nFileSizeHigh + FileSizeApi End With Else FileSizeApi = INVALID_HANDLE_VALUE End If End Function
From: bart.smissaert on 18 Nov 2009 11:46
OK, can't remember getting wrong results with the code I posted last, but maybe I missed that particular range. Will check it out. I take it it still makes sense to go with FindFirstFileW RBS > It was the IDE that changed the type declaration to Double. > > I've also spotted that the function messes up when checking a file which > is between 2GB & 4GB - you get a negative result, so here's one that works. > > Ian > > Public Const MAXDWORD As Currency = 4294967296@ > > Function FileSizeApi(ByVal FilePath As String) As Currency > Dim hFile As Long > Dim wfd As WIN32_FIND_DATA > hFile = FindFirstFile(FilePath, wfd) > If hFile <> INVALID_HANDLE_VALUE Then > FindClose hFile > With wfd > If .nFileSizeLow < 0 Then > FileSizeApi = MAXDWORD + .nFileSizeLow > Else > FileSizeApi = .nFileSizeLow > End If > FileSizeApi = MAXDWORD * .nFileSizeHigh + FileSizeApi > End With > Else > FileSizeApi = INVALID_HANDLE_VALUE > End If > End Function |