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cZipArchive

A single-class pure VB6 library for zip archives management

Usage

Just include cZipArchive.cls to your project and start using instances of the class like this:

Simple compression

With New cZipArchive
    .AddFile App.Path & "\your_file"
    .CompressArchive App.Path & "\test.zip"
End With

Compress all files and sub-folders

With New cZipArchive
    .AddFromFolder "C:\Path\To\*.*", Recursive:=True
    .CompressArchive App.Path & "\archive.zip"
End With

Decompress all files from archive

With New cZipArchive
    .OpenArchive App.Path & "\test.zip"
    .Extract "C:\Path\To\extract_folder"
End With

Method Extract can optionally filter on file mask (e.g. Filter:="*.doc"), file index (e.g. Filter:=15) or array of booleans with each entry to decompress index set to True.

Extract single file to target filename

OutputTarget can include a target new_filename to be used when extracting a specific file from the archive.

With New cZipArchive
    .OpenArchive App.Path & "\test.zip"
    .Extract "C:\Path\To\extract_folder\new_filename", Filter:="your_file"
End With

Get archive entry uncompressed size

By using FileInfo property keyed on entry filename in first parameter and zipIdxSize like this

With New cZipArchive
    .OpenArchive App.Path & "\test.zip"
    Debug.Print .FileInfo("report.pdf", zipIdxSize)
End With

List files in zip archive

By using FileInfo propery keyed on entry numeric index in first parameter like this

Dim lIdx            As Long
With New cZipArchive
    .OpenArchive App.Path & "\test.zip"
    For lIdx = 0 To .FileCount - 1
        Debug.Print "FileName=" & .FileInfo(lIdx, zipIdxFileName) & ", Size=" & .FileInfo(lIdx, zipIdxSize)
    Next
End With

Here is a list of available values for the second parameter of FileInfo:

Name
0 zipIdxFileName
1 zipIdxAttributes
2 zipIdxCrc32
3 zipIdxSize
4 zipIdxCompressedSize
5 zipIdxComment
6 zipIdxLastModified
7 zipIdxMethod
8 zipIdxOffset
9 zipIdxFlags

Encryption support

Make sure to set Conditional Compilation in Make tab in project's properties dialog to include ZIP_CRYPTO = 1 setting for crypto support to get compiled from sources. By default crypto support is not compiled to reduce footprint on the final executable size.

With New cZipArchive
    .OpenArchive App.Path & "\test.zip"
    .Extract App.Path & "\test", Password:="123456"
End With

Use Password parameter on AddFile method together with EncrStrength parameter to set crypto used when creating archive.

EncrStrength Mode
0 ZipCrypto (default)
1 AES-128
2 AES-192
3 AES-256 (recommended)

Note that default ZipCrypto encryption is weak but this is the only option which is compatible with Windows Explorer built-in zipfolders support.

In-memory operations

Sample utility function ReadBinaryFile in /test/basic/Form1.frm returns byte array with file's content.

Dim baZip() As Byte
With New cZipArchive
    .AddFile ReadBinaryFile("sample.pdf"), "report.pdf"
    .CompressArchive baZip
End With
WriteBinaryFile "test.zip", baZip

Method Extract accepts byte array target too.

Dim baOutput() As Byte
With New cZipArchive
    .OpenArchive ReadBinaryFile("test.zip")
    .Extract baOutput, Filter:=0    '--- archive's first file only
End With

ToDo (not supported yet)

- Deflate64 (de)compressor
- VBA7 (x64) support