GZIPStream Compression Always Returns 10 Bytes

Question

I'm trying to compress some text in my UWP application. I created this method to make it easier later on:

public static byte[] Compress(this string s)
{
    var b = Encoding.UTF8.GetBytes(s);
    using (MemoryStream ms = new MemoryStream())
    using (GZipStream zipStream = new GZipStream(ms, CompressionMode.Compress))
    {
        zipStream.Write(b, 0, b.Length);
        zipStream.Flush(); //Doesn't seem like Close() is available in UWP, so I changed it to Flush(). Is this the problem?
        return ms.ToArray();
    }
}

But unfortunately this always returns 10 bytes, no matter what the input text is. Is it because I don't use .Close() on the GZipStream?

score 7 · Accepted Answer · answered Oct 20 '16 at 08:50

You are returning the byte data too early. The Close() method is replaced by the Dispose() method. So the GZIP stream will be written only when disposed so after you leave the using(GZipStream) {} block.

public static byte[] Compress(string s)
{
    var b = Encoding.UTF8.GetBytes(s);
    var ms = new MemoryStream();
    using (GZipStream zipStream = new GZipStream(ms, CompressionMode.Compress))
    {
        zipStream.Write(b, 0, b.Length);
        zipStream.Flush(); //Doesn't seem like Close() is available in UWP, so I changed it to Flush(). Is this the problem?
    }

    // we create the data array here once the GZIP stream has been disposed
    var data    = ms.ToArray();
    ms.Dispose();
    return data;
}

Yep, that works like a charm! I tried using `.Dispose()` before, but instead of using it outside the using() block I just called it before returning the data, and that resulted in `ms` getting disposed of as well. Thanks! — Reynevan, Oct 20 '16 at 09:03

GZIPStream Compression Always Returns 10 Bytes

1 Answers1