(Tcl) Compress and Decompress Base64

Imagine we have data represented as a base64 string. This example demonstrates how to decode, compress, and re-encode to smaller base64 representing the compressed data.

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

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load ./chilkat.dll

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

set strBase64 "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NClRoZSBxdWljayBicm93biBmb3gganVtcGVkIG92ZXIgdGhlIGxhenkgZG9nLg0KVGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NCg0K"

set compress [new_CkCompression]

CkCompression_put_Algorithm $compress "deflate"

set binDat [new_CkBinData]

# Load the base64 data into a BinData object.
# This decodes the base64. The decoded bytes will be contained in the BinData.
CkBinData_AppendEncoded $binDat $strBase64 "base64"

# Compress the BinData.
CkCompression_CompressBd $compress $binDat

# Get the compressed data in base64 format:
set compressedBase64 [CkBinData_getEncoded $binDat "base64"]
puts "compressed base64:"
puts "$compressedBase64"

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

# Now decompress:
CkBinData_Clear $binDat
CkBinData_AppendEncoded $binDat $compressedBase64 "base64"
CkCompression_DecompressBd $compress $binDat

set decompressedBase64 [CkBinData_getEncoded $binDat "base64"]
puts "decompressed base64:"
puts "$decompressedBase64"

# The output is the original data:
# VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NClRoZSBxdWljayBicm93biBmb3gganVtcGVkIG92ZXIgdGhlIGxhenkgZG9nLg0KVGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZWQgb3ZlciB0aGUgbGF6eSBkb2cuDQpUaGUgcXVpY2sgYnJvd24gZm94IGp1bXBlZCBvdmVyIHRoZSBsYXp5IGRvZy4NCg0K

delete_CkCompression $compress
delete_CkBinData $binDat