Saturday, April 13, 2013

C# array compress and decompress with GZipStream

A small utility class for compressing and decompressing.

public static class Compression
{
    public static byte[] Compress(byte[] data)
    {
        using (var ms = new MemoryStream())
        {
            using (var gzip = new GZipStream(ms, CompressionLevel.Optimal))
            {
                gzip.Write(data, 0, data.Length);
            }
            data = ms.ToArray();
        }
        return data;
    }
    public static byte[] Decompress(byte[] data)
    {
        // the trick is to read the last 4 bytes to get the length
        // gzip appends this to the array when compressing
        var lengthBuffer = new byte[4];
        Array.Copy(data, data.Length - 4, lengthBuffer, 0, 4);
        int uncompressedSize = BitConverter.ToInt32(lengthBuffer, 0);
        var buffer = new byte[uncompressedSize];
        using (var ms = new MemoryStream(data))
        {
            using (var gzip = new GZipStream(ms, CompressionMode.Decompress))
            {
                gzip.Read(buffer, 0, uncompressedSize);
            }
        }
        return buffer;
    }
}


2 comments:

  1. Is there no way to toggle line numbers of or to do a clean copy?

    ReplyDelete
  2. Hi there,
    Thank you for your comment. Better late than sorry.
    I've started to cleanup all code posting on the blog and remove the annoying line numbers. Should be cleaner now.

    ReplyDelete