PPMD String Compression

Demonstrates string compression using PPMD.

Downloads for Windows/Linux and Install Instructions

require 'rubygems'
require 'chilkat'

compress = Chilkat::CkCompression.new()

#  Any string argument automatically begins a 30-day trial.
success = compress.UnlockComponent("30-day trial")
if (success != true)
    print "Compression component unlock failed" + "\n"
    exit
end

compress.put_Algorithm("ppmd")

#  Create a long string to compress.
strData = "abcdefg1122334455667788"
strData = strData + "\r\n"
for i in 0 .. 99
    strData = strData + "abcdefg1122334455667788"
    strData = strData + "\r\n"
end

#  Depending on the programming language, the string
#  may be Unicode.  Tell the component to convert to
#  ansi (1-byte/char) prior to compression:
compress.put_Charset("ansi")

#  Compressed data is binary, meaning that all byte values
#  from 0 to 255 are possible.  The result would not be
#  a printable string.  To receive a printable string (us-ascii),
#  the resultant compressed data should be encoded using
#  an encoding such as base64.  Set the EncodingMode
#  property to determine the output encoding:
#  (Valid choices are "base64", "hex", "url", and others)
compress.put_EncodingMode("base64")

#  Note: Base64 encoding expands the compressed data by
#  4/3rds because each 3 bytes of binary data are represented
#  by 4 printable chars.  Hex, for example, doubles the output
#  size because each byte is represented by 2 printable chars.

#  PPMD compress the string:

compressedStr = compress.compressStringENC(strData)
if (compressedStr == nil )
    print compress.lastErrorText() + "\n"
    exit
end

#  Display the compressed string.
#  The result will be:
#  ec8YZ5vk9za18d0plwuV7R65em9OZge9gJXht/QAAAAAAAAAABNOZQAAKw==
print compressedStr + "\n";

#  Decompress back to the original:

strOriginal = compress.decompressStringENC(compressedStr)

#  Display the uncompressed original:
print "--- Original ---" + "\n";
print strOriginal + "\n";