Open Read Write Close API ?

[WideAwake]

I searched this forum and other places on the web and found a few people ask how to open and close files using the API, though I've never actually seen a way of doing this as most replies say just use the VB I/O OPEN and CLOSE.

Example, is there an API equivelent of this: (Line input important)

'READ
Dim FileNum As Integer
FileNum = FreeFile
Open (App.Path & "\myfile.txt") For Input As FileNum
Do While Not EOF(FileNum)
ReDim Preserve myARRAY$(count)
Line Input #FileNum, myARRAY$(count)
count = count + 1
Loop
Close FileNum

'WRITE
Dim FileNum As Integer
FileNum = FreeFile
Open (App.Path & "\myfile.txt") For OutPut As FileNum
Print #FileNum, myText$
Close FileNum

Sorry if there's a 'typo' but I think you get the 'jist'.
I'd be really greatful if anyone could give me the equivelent API of this OPEN, READ (line) or WRITE, CLOSE.

TIA

[jim mcnamara]

Here's sample file i/o in api.

Const MOVEFILE_REPLACE_EXISTING = &H1
Const FILE_ATTRIBUTE_TEMPORARY = &H100
Const FILE_BEGIN = 0
Const FILE_SHARE_READ = &H1
Const FILE_SHARE_WRITE = &H2
Const CREATE_NEW = 1
Const OPEN_EXISTING = 3
Const GENERIC_READ = &H80000000
Const GENERIC_WRITE = &H40000000
Private Declare Function SetVolumeLabel Lib "kernel32" Alias "SetVolumeLabelA" (ByVal lpRootPathName As String, ByVal lpVolumeName As String) As Long
Private Declare Function WriteFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, lpNumberOfBytesWritten As Long, ByVal lpOverlapped As Any) As Long
Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, ByVal lpOverlapped As Any) 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 CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function SetFilePointer Lib "kernel32" (ByVal hFile As Long, ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, ByVal dwMoveMethod As Long) As Long
Private Declare Function SetFileAttributes Lib "kernel32" Alias "SetFileAttributesA" (ByVal lpFileName As String, ByVal dwFileAttributes As Long) As Long
Private Declare Function GetFileSize Lib "kernel32" (ByVal hFile As Long, lpFileSizeHigh As Long) As Long
Private Declare Function GetTempFileName Lib "kernel32" Alias "GetTempFileNameA" (ByVal lpszPath As String, ByVal lpPrefixString As String, ByVal wUnique As Long, ByVal lpTempFileName As String) As Long
Private Declare Function MoveFileEx Lib "kernel32" Alias "MoveFileExA" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal dwFlags As Long) As Long
Private Declare Function DeleteFile Lib "kernel32" Alias "DeleteFileA" (ByVal lpFileName As String) As Long
Private Sub Form_Load()
    'KPD-Team 1998
    'URL: http://www.allapi.net/
    'E-Mail: [email protected]
    Dim sSave As String, hOrgFile As Long, hNewFile As Long, bBytes() As Byte
    Dim sTemp As String, nSize As Long, Ret As Long
    'Ask for a new volume label
    sSave = InputBox("Please enter a new volume label for drive C:\" + vbCrLf + " (if you don't want to change it, leave the textbox blank)")
    If sSave <> "" Then
        SetVolumeLabel "C:\", sSave
    End If
    
    'Create a buffer
    sTemp = String(260, 0)
    'Get a temporary filename
    GetTempFileName "C:\", "KPD", 0, sTemp
    'Remove all the unnecessary chr$(0)'s
    sTemp = Left$(sTemp, InStr(1, sTemp, Chr$(0)) - 1)
    'Set the file attributes
    SetFileAttributes sTemp, FILE_ATTRIBUTE_TEMPORARY
    'Open the files
    hNewFile = CreateFile(sTemp, GENERIC_WRITE, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0)
    hOrgFile = CreateFile("c:\config.sys", GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0)
    
    'Get the file size
    nSize = GetFileSize(hOrgFile, 0)
    'Set the file pointer
    SetFilePointer hOrgFile, Int(nSize / 2), 0, FILE_BEGIN
    'Create an array of bytes
    ReDim bBytes(1 To nSize - Int(nSize / 2)) As Byte
    'Read from the file
    ReadFile hOrgFile, bBytes(1), UBound(bBytes), Ret, ByVal 0&
    'Check for errors
    If Ret <> UBound(bBytes) Then MsgBox "Error reading file ..."
    
    'Write to the file
    WriteFile hNewFile, bBytes(1), UBound(bBytes), Ret, ByVal 0&
    'Check for errors
    If Ret <> UBound(bBytes) Then MsgBox "Error writing file ..."
    
    'Close the files
    CloseHandle hOrgFile
    CloseHandle hNewFile
    
    'Move the file
    MoveFileEx sTemp, "C:\KPDTEST.TST", MOVEFILE_REPLACE_EXISTING
    'Delete the file
    DeleteFile "C:\KPDTEST.TST"
    Unload Me
End Sub

[Richyrich]

Would this be significantly quicker than using a file handle?

[jim mcnamara]

Not particulary. File i/o rates are governed by disk i/o rates, which is usually 1000x slower than the cpu.

The only real use for this is with memory-mapped files (files that reside in memory during program execution rather than on disk)