PPMD Streaming String Compression

Demonstrates streaming string compression using PPMD. Data may be compressed in chunks by initially calling one of the BeginCompress* methods, followed by 0 or more calls to a MoreCompress* method, and terminating with a call to an EndCompress* method.

Likewise, data may be decompressed by calling a BeginDecompress* method, followed by 0 or more MoreDecompress* calls, and ending with an EndDecompress* method call.

This example demonstrates string-to-string compression and decompression in chunks.

Download: Chilkat .NET Assemblies

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";
compress.Charset = "ansi";
compress.EncodingMode = "base64";

string strData;
int i;

string strCompressed;

//  Create a long string to compress.
strData = "abcdefg1122334455667788";
strData = strData + "\r\n";

//  Note: BeginCompressStringENC may return a zero-length
//  string.  This is normal if the input is buffered and no
//  compressed data is yet available.
//  However, a null reference indicates an error -- which is
//  generally only possible if the component was never unlocked.
strCompressed = compress.BeginCompressStringENC(strData);

//  Compress 100 more chunks of data.  Each call to
//  MoreCompressStringENC may or may not produce additional
//  compressed output.
for (i = 0; i <= 99; i++) {
    strData = "abcdefg1122334455667788";
    strData = strData + "\r\n";

    strCompressed = strCompressed + compress.MoreCompressStringENC(strData);
}

//  Finalize the compression with a single call to EndCompressStringENC:
strCompressed = strCompressed + compress.EndCompressStringENC();

//  Display the compressed string.
//  The result will be:
//  ec8YZ5vk9za18d0plwuV7R65em9OZge9gJXht/QAAAAAAAAAABNOZQAAKw==

textBox1.Text += strCompressed + "\r\n";

//  Decompress back to the original in a single call.
string strOriginal;
strOriginal = compress.DecompressStringENC(strCompressed);

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

//  Decompress in multiple calls.  It doesn't matter how the
//  compressed data is split -- it could be fed to the decompressor
//  one char at a time if desired.
string chunk1;
chunk1 = "ec8YZ5vk9za1";
string chunk2;
chunk2 = "8d0p";
string chunk3;
chunk3 = "lwuV7R65em9OZge9gJXht/QAAAA";
string chunk4;
chunk4 = "AAAAAABNOZQAAKw==";

strOriginal = "";
strOriginal = compress.BeginDecompressStringENC(chunk1);
strOriginal = strOriginal + compress.MoreDecompressStringENC(chunk2);
strOriginal = strOriginal + compress.MoreDecompressStringENC(chunk3);
strOriginal = strOriginal + compress.MoreDecompressStringENC(chunk4);
strOriginal = strOriginal + compress.EndDecompressStringENC();

//  Display the uncompressed original after decompressing in chunks:
textBox1.Text += "--- Original after Decompressing from Chunks ---" + "\r\n";
textBox1.Text += strOriginal + "\r\n";