PPMD Compress File

Demonstrates how to use the PPMD compression algorithm to compress a file. This code is capable of compressing any size file because the file data is compressed from input to output in a streaming mode. The output file does not contain any "PPMD" header -- it is purely PPMD compressed data.

Download the Chilkat Compression ActiveX here: ChilkatCompression.zip
Unzip and register the DLL with regsvr32. (This is a pre-release)

Dim compress As New ChilkatCompression

'  Any string argument automatically begins a 30-day trial.
Dim success As Long
success = compress.UnlockComponent("30-day trial")
If (success <> 1) Then
    MsgBox "Compression component unlock failed"
    Exit Sub
End If

compress.Algorithm = "ppmd"

success = compress.CompressFile("hamlet.xml","hamletPpmd.dat")
If (success <> 1) Then
    MsgBox compress.LastErrorText
    Exit Sub
End If

'  Decompress back to the original:
success = compress.DecompressFile("hamletPpmd.dat","hamletInflated.xml")
If (success <> 1) Then
    MsgBox compress.LastErrorText
    Exit Sub
End If

Text1.Text = Text1.Text & "Success!" & vbCrLf