Writing compressed gzipstream to a file

Question

I have a gzipstream that is compressed and I want to write it to a file. Now the problem is that the Read is not supported on the gzipstream that is compressed. Below is my code where the gzipstream reads the stream from a memorystream and then I want to write it to a filestream.

using (var stream = new MemoryStream())
{
    using (FileStream file = new FileStream(@"c:\newest.xml.gz", 
        FileMode.Create, FileAccess.Write))
    {
        using (GZipStream gzs = new GZipStream(file, CompressionLevel.Fastest))
        {
            stream.CopyTo(gzs);
        }
    }  
}

Any idea how I can create a filestream from a compressed gzipstream?

EDIT:

That was my bad, sorry to have waste your time. For future reference the code above should work, the problem was somewhere else.

Why do you want to compress `stream` and then decompress it? — Ahmed KRAIEM, Oct 11 '13 at 09:44
Essentially I need to compress the file and store it as .gz in my file system... — Rob Schneider, Oct 11 '13 at 09:48
Then why are you using `gzs` with `CompressionMode.Decompress`? — Ahmed KRAIEM, Oct 11 '13 at 09:52
I was about to post an answer about how to write to a compressed file but after you have changed you question you are doing it correctly and as far as I can see you should no longer encounter the error you describe. — Martin Liversage, Oct 11 '13 at 10:04
Yes Martin, I realised what I was doing wrong there. But now although my stream is not empty, I get an empty compressed file? Any idea? — Rob Schneider, Oct 11 '13 at 10:08

score 1 · Answer 1 · answered Oct 11 '13 at 10:00

You seem to be reading and writing the same memory stream. I don't think that's possible; you should use two different streams: one from which you read, and another into which you write:

using (gzipStream = new GZipStream(writeStream,CompressionLevel.Fastest))
{
    readStream.CopyTo(gzipStream);
}

Writing compressed gzipstream to a file

1 Answers1