Question

I am trying to understand why my code doesn’t execute as desired. It creates a GZipStream, and then saves the object as compressed file on my hard drive, but the saved file is always 0 bytes.

Now I know how to save a file using GZipStream, but, my question is not how to do it. My question is purely why does this code save 0 bytes (or why FileStream works and memory doesn’t).

private void BegingCompression()
{
    var bytes = File.ReadAllBytes(this.fileName);
    using (MemoryStream ms = new MemoryStream(bytes))
    {
        ms.ReadByte();
        using (FileStream fs =new FileStream(this.newFileName, FileMode.CreateNew))
        using (GZipStream zipStream = new GZipStream(ms, CompressionMode.Compress, false))
        {
            zipStream.Write(bytes, 0, bytes.Length);
        }
    }
}

In regards to the source code, this.fileName = c:\Audio.wav and the newFileName is c:\Audio.wav.gz (but have also tried c:\audio.gz)

Answer 1

• You do not need a MemoryStream because bytes already has the data to compress.
• ms.ReadByte() should not be used.
• When creating the zipStream the output file stream should be used.

Try this:

var bytes = File.ReadAllBytes(this.fileName);
using (FileStream fs =new FileStream(this.newFileName, FileMode.CreateNew))
using (GZipStream zipStream = new GZipStream(fs, CompressionMode.Compress, false))
{
     zipStream.Write(bytes, 0, bytes.Length);
}

EDIT

The original code creates a zero length file because you do not write to the file stream.