(PureBasic) Compress and Decompress Hex String

Imagine we have data represented as a hex string. This example demonstrates how to decode, compress, and re-encode to a smaller hex string representing the compressed data. An even better choice is to re-encode to a more compact encoding such as base64.

Note: This example requires Chilkat v9.5.0.66 or greater.

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IncludeFile "CkBinData.pb"
IncludeFile "CkCompression.pb"

Procedure ChilkatExample()

    ; This example assumes the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    success.i

    strHex.s = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

    compress.i = CkCompression::ckCreate()
    If compress.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkCompression::setCkAlgorithm(compress, "deflate")

    binDat.i = CkBinData::ckCreate()
    If binDat.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Load the hex string into a BinData object.
    ; This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
    CkBinData::ckAppendEncoded(binDat,strHex,"hex")

    ; Compress the BinData.
    CkCompression::ckCompressBd(compress,binDat)

    ; Get the compressed data in hex format:
    compressedHex.s = CkBinData::ckGetEncoded(binDat,"hex")
    Debug "compressed hex:"
    Debug compressedHex

    ; The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

    ; Even better, get the compressed data in base64 format:
    ; (base64url and modbase64 are other valid choices...)
    compressedBase64.s = CkBinData::ckGetEncoded(binDat,"base64")
    Debug "compressed base64:"
    Debug compressedBase64

    ; The compressed base64 is: C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

    ; Now decompress:
    CkBinData::ckClear(binDat)
    CkBinData::ckAppendEncoded(binDat,compressedHex,"hex")
    CkCompression::ckDecompressBd(compress,binDat)

    decompressedHex.s = CkBinData::ckGetEncoded(binDat,"hex")
    Debug "decompressed hex:"
    Debug decompressedHex

    ; The output is the original hex string:
    ; 54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A


    CkCompression::ckDispose(compress)
    CkBinData::ckDispose(binDat)


    ProcedureReturn
EndProcedure