PPMD String Compression

Demonstrates string compression using PPMD.

The functionality in this example is available in pre-release only:
To use, unzip and add a reference to the enclosed DLL in your .NET project.

Download Chilkat .NET for 2.0 / 3.5 Framework

Download Chilkat .NET for 1.0 / 1.1 Framework

Chilkat.Compression compress = new Chilkat.Compression();

//  Any string argument automatically begins a 30-day trial.
bool success;
success = compress.UnlockComponent("30-day trial");
if (success != true) {
    MessageBox.Show("Compression component unlock failed");
    return;
}

compress.Algorithm = "ppmd";

string strData;
int i;

//  Create a long string to compress.
strData = "abcdefg1122334455667788";
strData = strData + "\r\n";
for (i = 0; i <= 99; i++) {
    strData = strData + "abcdefg1122334455667788";
    strData = strData + "\r\n";
}

//  Depending on the programming language, the string
//  may be Unicode.  Tell the component to convert to
//  ansi (1-byte/char) prior to compression:
compress.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.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:
string compressedStr;
compressedStr = compress.CompressStringENC(strData);
if (compressedStr == null ) {
    MessageBox.Show(compress.LastErrorText);
    return;
}

//  Display the compressed string.
//  The result will be:
//  ec8YZ5vk9za18d0plwuV7R65em9OZge9gJXht/QAAAAAAAAAABNOZQAAKw==
textBox1.Text += compressedStr + "\r\n";

//  Decompress back to the original:
string strOriginal;
strOriginal = compress.DecompressStringENC(compressedStr);

//  Display the uncompressed original:
textBox1.Text += "--- Original ---" + "\r\n";
textBox1.Text += strOriginal + "\r\n";