System.IO.Compression.GZipStream Class

Provides methods and properties used to compress and decompress streams.

See Also: GZipStream Members


public class GZipStream : System.IO.Stream


This class represents the gzip data format, which uses an industry-standard algorithm for lossless file compression and decompression. The format includes a cyclic redundancy check value for detecting data corruption. The gzip data format uses the same algorithm as the System.IO.Compression.DeflateStream class, but can be extended to use other compression formats. The format can be readily implemented in a manner not covered by patents.

Starting with the net_v45, the System.IO.Compression.DeflateStream class uses the zlib library for compression. As a result, it provides a better compression algorithm and, in most cases, a smaller compressed file than it provides in earlier versions of the .NET Framework.

Compressed System.IO.Compression.GZipStream objects written to a file with an extension of .gz can be decompressed using many common compression tools; however, this class does not inherently provide functionality for adding files to or extracting files from zip archives.

The compression functionality in System.IO.Compression.DeflateStream and System.IO.Compression.GZipStream is exposed as a stream. Data is read on a byte-by-byte basis, so it is not possible to perform multiple passes to determine the best method for compressing entire files or large blocks of data. The System.IO.Compression.DeflateStream and System.IO.Compression.GZipStream classes are best used on uncompressed sources of data. If the source data is already compressed, using these classes may actually increase the size of the stream.


Namespace: System.IO.Compression
Assembly: System (in System.dll)
Assembly Versions:,
Since: .NET 2.0