Lua Requires Chilkat v9.5.0.66+

Compress and Decompress Hex String

See more Compression Examples

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. Lua

local chilkat = require("chilkat")

local success = false

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

local strHex = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

local compress = chilkat.Compression.new()
compress.algorithm = "deflate"

local binDat = chilkat.BinData.new()
-- Load the hex string into a BinData object.
-- This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
binDat:append_encoded(strHex, "hex")

-- Compress the BinData.
compress:compress_bd(binDat)

-- Get the compressed data in hex format:
local compressedHex = binDat:get_encoded("hex")
print("compressed hex:")
print(compressedHex)

-- The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

-- Even better, get the compressed data in base64 format:
-- (base64url and modbase64 are other valid choices...)
local compressedBase64 = binDat:get_encoded("base64")
print("compressed base64:")
print(compressedBase64)

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

-- Now decompress:
binDat:clear()
binDat:append_encoded(compressedHex, "hex")
compress:decompress_bd(binDat)

local decompressedHex = binDat:get_encoded("hex")
print("decompressed hex:")
print(decompressedHex)

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