How To Use LZCopy to Copy Files (200649)


The information in this article applies to:

  • Microsoft Visual Basic Enterprise Edition for Windows 5.0
  • Microsoft Visual Basic Enterprise Edition for Windows 6.0
  • Microsoft Visual Basic Professional Edition for Windows 5.0
  • Microsoft Visual Basic Professional Edition for Windows 6.0
  • Microsoft Visual Basic Learning Edition for Windows 5.0
  • Microsoft Visual Basic Learning Edition for Windows 6.0
This article was previously published under Q200649

SUMMARY

This article demonstrates how to use the LZOpenFile, LZCopy, and LZClose functions from the LZ Expand/Compress library (LZ32.dll). You can use these functions to make a copy of an existing file. The LZCopy function creates a decompressed destination file if the source file is compressed with the Microsoft File Compression Utility (Compress.exe).

MORE INFORMATION

Step-by-Step Example

These steps demonstrate how to use the functions from the LZ Expand/Compress library to copy files to and from locations on a local or network drive.
  1. Create a new Standard EXE project. Form1 is created by default.
  2. Add two Labels, two TextBoxes, and a CommandButton to Form1.
  3. Position Label1 and Label2 above Text1 and Text2, respectively.
  4. Add the following code to the General Declarations section of Form1:
    Option Explicit

Const OF_CREATE = &H1000
Const OF_READ = &H0
Const OFS_MAXPATHNAME = 128

Private Type OFSTRUCT
    cBytes As Byte
    fFixedDisk As Byte
    nErrCode As Integer
    Reserved1 As Integer
    Reserved2 As Integer
    szPathName(OFS_MAXPATHNAME) As Byte
End Type

Private Declare Sub LZClose Lib "lz32.dll" _
        (ByVal hfFile As Long)
Private Declare Function LZCopy Lib "lz32.dll" _
        (ByVal hfSource As Long, ByVal hfDest As Long) As Long
Private Declare Function LZOpenFile Lib "lz32.dll" Alias "LZOpenFileA" _
        (ByVal lpszFile As String, lpOf As OFSTRUCT, ByVal style As Long) _
        As Long

Public Sub CopyFile(Source As String, Destination As String)
    Dim hsource As Long
    Dim hdest As Long
    Dim iret As Long
    Dim OpenStruct As OFSTRUCT

    ' Open the source and destination files.
    hsource = LZOpenFile(Source, OpenStruct, OF_READ)
    hdest = LZOpenFile(Destination, OpenStruct, OF_CREATE)
    ' Copy the source file to the destination location, and
    ' decompress the Source file if it was compressed.
    iret = LZCopy(hsource, hdest)
    ' Close the files.
    LZClose hdest
    LZClose hsource
    If iret = -1 Then
        MsgBox "File transfer failed"
    Else
        MsgBox "Transfer successful: " _
        & Format$(iret, "###,###,###,###") _
        & " bytes were transferred."
    End If
End Sub

Private Sub Command1_Click()
    CopyFile Text1.Text, Text2.Text
End Sub

Private Sub Form_Load()
    Label1.Caption = "Source Directory and Filename"
    Label2.Caption = "Target Directory and Filename"
    Command1.Caption = "Copy"
End Sub
  5. Run the project. In the Source TextBox, type the full path and file name of the file that you want to copy.
  6. In the Target TextBox, type the full path and file name of the destination file, and then click Copy.
  7. In Windows Explorer, confirm that the file copied successfully.

REFERENCES

For more information about these functions, see the following MSDN documentation:

LZOpenFile
http://msdn.microsoft.com/library/psdk/winbase/datadcmp_1tyd.htm

LZCopy
http://msdn.microsoft.com/library/psdk/winbase/datadcmp_9b3t.htm

LZClose
http://msdn.microsoft.com/library/psdk/winbase/datadcmp_8skl.htm

Modification Type:MinorLast Reviewed:7/13/2004
Keywords:kbAPI kbFileIO kbhowto KB200649
©2004 Microsoft Corporation. All rights reserved.