(Visual FoxPro) 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL lcStrHex
LOCAL loCompress
LOCAL loBinDat
LOCAL lcCompressedHex
LOCAL lcCompressedBase64
LOCAL lcDecompressedHex

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

lcStrHex = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Compression')
loCompress = CreateObject('Chilkat.Compression')
loCompress.Algorithm = "deflate"

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBinDat = CreateObject('Chilkat.BinData')
* Load the hex string into a BinData object.
* This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
loBinDat.AppendEncoded(lcStrHex,"hex")

* Compress the BinData.
loCompress.CompressBd(loBinDat)

* Get the compressed data in hex format:
lcCompressedHex = loBinDat.GetEncoded("hex")
? "compressed hex:"
? lcCompressedHex

* The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

* Even better, get the compressed data in base64 format:
* (base64url and modbase64 are other valid choices...)
lcCompressedBase64 = loBinDat.GetEncoded("base64")
? "compressed base64:"
? lcCompressedBase64

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

* Now decompress:
loBinDat.Clear()
loBinDat.AppendEncoded(lcCompressedHex,"hex")
loCompress.DecompressBd(loBinDat)

lcDecompressedHex = loBinDat.GetEncoded("hex")
? "decompressed hex:"
? lcDecompressedHex

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

RELEASE loCompress
RELEASE loBinDat