Microsoft KB Archive/102671

= ACC: Sample Function CopyFile to Copy Disk Files =

Article ID: 102671

Article Last Modified on 5/6/2003

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APPLIES TO


 * Microsoft Access 1.0 Standard Edition
 * Microsoft Access 1.1 Standard Edition
 * Microsoft Access 2.0 Standard Edition

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This article was previously published under Q102671



SUMMARY
Advanced: Requires expert coding, interoperability, and multiuser skills.

Access Basic does not have a command, such as the MS-DOS COPY command, to copy a disk file.

This article includes two variations of an Access Basic function called CopyFile, both of which allow you to copy disk files.

This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information on Access Basic, please refer to the "Introduction to Programming" manual in Microsoft Access version 1.x, or the "Building Applications" manual, Chapter 3, "Introducing Access Basic" in version 2.0.

NOTE: Microsoft Access for Windows 95 can copy files with the new FileCopy statement. For more information about FileCopy, search for "FileCopy Statement" using the Microsoft Access for Windows 95 Help Index.



MORE INFORMATION
Two variations of the Access Basic CopyFile function are provided below. The first version uses only Microsoft Access Basic code; the second leverages some function calls to the Windows application programming interface (API) to optimize performance, particularly with larger files.

NOTE: You may have some Windows API functions defined in an existing Microsoft Access library; therefore, your declarations may be duplicates. If you receive the duplicate procedure name error message when you compile or run your code, remove or comment out the appropriate declarations statement from your code.

Method 1: CopyFile Function Using Standard Access Basic Code
  '************************************************************** ' DECLARATION SECTION '**************************************************************  Option Explicit

'**************************************************************  ' FUNCTION: CopyFile ' PURPOSE: '  Facilitates copying a disk file. ' ARGUMENTS: '  Source      - The path\filename of the file to copy from. '  Destination - The path\filename of the file to copy to. ' RETURN: '  The length of the file copied. '**************************************************************  Function CopyFile (ByVal Source$, ByVal Destination$) As Long Dim Index1 As Integer, NumBlocks As Integer Dim FileLength As Long, LeftOver As Long, AmountCopied As Long Dim SourceFile As Integer, DestFile As Integer Dim FileData As String Dim RetVal As Variant Const BlockSize = 32768

On Error GoTo Err_CopyFile

' Remove the destination file. DestFile = FreeFile Open Destination For Output As DestFile Close DestFile

' Open the source file to read from. SourceFile = FreeFile Open Source For Binary Access Read As FreeFile

' Open the destination file to write to. DestFile = FreeFile Open Destination For Binary As DestFile

' Get the length of the source file. FileLength = LOF(SourceFile)

' Calculate the number of blocks in the file and left over. NumBlocks = FileLength \ BlockSize LeftOver = FileLength Mod BlockSize

' Create a buffer for the leftover amount. FileData = String$(LeftOver, 32)

' Read and write the leftover amount. Get SourceFile,, FileData Put DestFile,, FileData

' Create a buffer for a block to be read. FileData = String$(BlockSize, 32)

' Read and write the remaining blocks of data. For Index1 = 1 To NumBlocks ' Read and write one block of data. Get SourceFile,, FileData Put DestFile,, FileData Next Index1

Close SourceFile, DestFile CopyFile = AmountCopied

Bye_CopyFile: Exit Function

Err_CopyFile: CopyFile = -1 * Err Resume Bye_CopyFile

End Function

Method 2: CopyFile Function Using Windows API function calls
  '**************************************************************** ' DECLARATION SECTION '****************************************************************  Declare Function fWrite Lib "kernel" Alias "_lwrite" (ByVal hFile%, _                       ByVal lpBuff&, ByVal nBuff%) As Long Declare Function fRead Lib "kernel" Alias "_lread" (ByVal hFile%, _                      ByVal lpBuff&, ByVal nBuff%) As Long Declare Function GlobalAlloc Lib "Kernel" (ByVal wFlags%, _                      ByVal dwBytes&) As Integer Declare Function GLobalFree Lib "kernel" (ByVal hMem%) As Long Declare Function GlobalLock Lib "Kernel" (ByVal hMem%) As Long Declare Function GLobalUnlock Lib "kernel" (ByVal hMem%) As Long

'****************************************************************  ' FUNCTION: CopyFile ' PURPOSE: '  Facilitates copying a disk file. ' ARGUMENTS: '  Source      - The path\filename of the file to copy from. '  Destination - The path\filename of the file to copy to. ' RETURN: '  The length of the file copied, if successful. '***********************************************************  Function CopyFile (ByVal Source$, ByVal Destination$) As Long Dim FileLength As Long, AmountCopied As Long Dim RetVal As Variant, lpBuff As Long Dim DestFile As Integer, SourceFile As Integer Dim DestDOS As Integer, SourceDOS As Integer Dim ApiErr As Integer, AmtRead As Integer Dim hMem As Integer Const nBuff = 32767 Const wFlags = &H20

On Error GoTo Err_CopyFile

' Get the size of the file. SourceFile = FreeFile Open Source For Binary Access Read As SourceFile FileLength = LOF(SourceFile) Close SourceFile

' Allocate and lock memory to buffer file contents. hMem = GlobalAlloc(wFlags, nBuff) lpBuff = GlobalLock(hMem)

' Open the source file to read from. SourceFile = FreeFile Open Source For Input As SourceFile Len = 1

' Open the destination file to write to. DestFile = FreeFile Open Destination For Output As DestFile Len = 1

' Get the operating system file handles. DestDOS = FileAttr(DestFile, 2) SourceDOS = FileAttr(SourceFile, 2)

Do         ' Read and write nBuff worth of data. AmtRead = fRead(SourceDOS, ByVal lpBuff, nBuff) ApiErr = fWrite(DestDOS, ByVal lpBuff, AmtRead) AmountCopied = AmountCopied + AmtRead Loop Until AmtRead = 0

Close SourceFile, DestFile

' Unlock and free the file buffer memory. lpBuff = GLobalUnlock(hMem) hMem = GLobalFree(hMem)

CopyFile = AmountCopied

Bye_CopyFile: Exit Function

Err_CopyFile: CopyFile = -1 * Err Resume Bye_CopyFile End Function

The CopyFile function can be tested from the Immediate window, as follows:

 Create or open a module in Microsoft Access. From the View menu, choose Immediate Window.  Type the following line, and then press ENTER:

? CopyFile("C:\WINDOWS\CHESS.BMP", "C:\CHESS.BMP")

The CopyFile function can be invoked from an Access Basic function

     Dim RetVal As Long RetVal = CopyFile("C:\WINDOWS\CHESS.BMP", "C:\CHESS.BMP")

or by using the RunCode macro action:

     RunCode Function Name: CopyFile("C:\WINDOWS\CHESS.BMP", "C:\CHESS.BMP")



Additional query words: copy files api

Keywords: kbinfo kbprogramming KB102671

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