Compression

[tyonuts]

Hi all, i just want to ask if anyone has some ideas (or links) about compression algorhytms (with examples). I have tried to find the source for ZIP, but I can't seem to get to it, although i know it's there.

 

[ManicCW]

isn't zip format patent protected by the law? but then again there are a lot of programs that use it!

 

[tyonuts]

no it isn't. Otherwise, i wouldn't have known about the source. one idea, try to search a linux source if u don't find the link to zip... i'll search it myself

 

[cjard]

some aspects of zip are based on the LZW compression, which is proprietary, but most of the zip spec should be available.
http://en.wikipedia.org/wiki/ZIP_file_format has more information.

i'd be interested to know why youre planning to reinvent this particular wheel?

 

[JohnH]

Best known open-source zip library is the SharpZipLib http://www.icsharpcode.net/OpenSource/SharpZipLib/ perhaps useful to see this implementation, even if it's in C# at least it's managed .Net. Includes Zip, GZip, Tar and BZip2 in libraries.

Note that .Net 2.0 has got new compression support in System.IO.Compression namespace, it's DeflateStream/GzipStream both based on Deflate algorithm, which uses a combination of the LZ77 algorithm and Huffman coding. Useful for applications internal compression needs, but I don't think you can use it to work with file structure archives like regular zip files. (if you make a compressed file from .Net any Zip application can decompress the content though)