CODEWITHSUNDEEP
c#memorystreamdeflate
A191919
A191919

Reputation: 3462

DeflateStream CopyTo MemoryStream

Tyring to compress and decompress MemoryStream but it seems that CopyTo does not work like it's expected? Why? How to fix this?

public static MemoryStream Compress(MemoryStream originalStream)
{
    Console.WriteLine("Original before compressing size: {0}", originalStream.Length.ToString());
    MemoryStream compressedMemoryStream = new MemoryStream();

    using (DeflateStream deflateStream = new DeflateStream(compressedMemoryStream, CompressionMode.Compress, true))
    {
        originalStream.CopyTo(deflateStream);
    }
    Console.WriteLine("Compressed size: {0}", compressedMemoryStream.Length.ToString());
    return compressedMemoryStream;
}

public static void Decompress(MemoryStream compressedStream)
{
    Console.WriteLine("Compressed before decompressing size: {0}", compressedStream.Length.ToString());
    using (MemoryStream decompressedFileStream = new MemoryStream())
    {
         using (DeflateStream decompressionStream = new DeflateStream(compressedStream, CompressionMode.Decompress, true))
         {
              decompressionStream.CopyTo(decompressedFileStream);
         }
         Console.WriteLine("Decompressed size: {0}", decompressedFileStream.Length.ToString());
    }
}

Output:

Original before compressing size: 5184054
Compressed size: 0
Compressed before decompressing size: 0
Decompressed size: 0

Upvotes: 5

Views: 1939

Answers (1)

Ray
Ray

Reputation: 8871

CopyTo starts copying bytes from the current position of the source stream.

Since you posted the resulting compressed stream size being 0, I'm pretty sure that originalStream is positioned at the end of the stream, so no bytes were copied / compressed.

Ensure the position is 0 so it can find any data to copy and compress to your stream.

As @xanatos mentioned, the same applies to Decompress, so ensure that compressedStream is positioned at 0 too before decompressing it.

Upvotes: 6

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