Create a Zip from to a memory stream or byte array

Code Reference / Zip Samples / Create a Zip from to a memory stream or byte array

This sample concentrates on the differences for memorystream output, the most important of which is setting IsStreamOwner = false so that the Close (which is needed to finish up the output) does not close the underlying memorystream. For multiple entries, passwords, etc, see the code sample above.

using ICSharpCode.SharpZipLib.Zip;

// Compresses the supplied memory stream, naming it as zipEntryName, into a zip,
// which is returned as a memory stream or a byte array.
public MemoryStream CreateToMemoryStream(MemoryStream memStreamIn, string zipEntryName) {

    var outputMemStream = new MemoryStream();
    using(var zipStream = new ZipOutputStream(outputMemStream)){

        // 0-9, 9 being the highest level of compression
        zipStream.SetLevel(3); 

        ZipEntry newEntry = new ZipEntry(zipEntryName);
        newEntry.DateTime = DateTime.Now;

        zipStream.PutNextEntry(newEntry);

        StreamUtils.Copy(memStreamIn, zipStream, new byte[4096]);
        zipStream.CloseEntry();

        // Stop ZipStream.Dispose() from also Closing the underlying stream.
        zipStream.IsStreamOwner = false;	
    }

    outputMemStream.Position = 0;
    return outputMemStream;

    // Alternative outputs:
    // ToArray is the cleaner and easiest to use correctly with the penalty of duplicating allocated memory.
    byte[] byteArrayOut = outputMemStream.ToArray();

    // GetBuffer returns a raw buffer raw and so you need to account for the true length yourself.
    byte[] byteArrayOut = outputMemStream.GetBuffer();
    long len = outputMemStream.Length;

}

Imports ICSharpCode.SharpZipLib.Zip

' Compresses the supplied memory stream, naming it as zipEntryName, into a zip,
' which is returned as a memory stream or a byte array.
'
Public Function CreateToMemoryStream(memStreamIn As MemoryStream, zipEntryName As String) As MemoryStream

    Dim outputMemStream As New MemoryStream()
    Dim zipStream As New ZipOutputStream(outputMemStream)

    zipStream.SetLevel(3)		'0-9, 9 being the highest level of compression
    Dim newEntry As New ZipEntry(zipEntryName)
    newEntry.DateTime = DateTime.Now

    zipStream.PutNextEntry(newEntry)

    StreamUtils.Copy(memStreamIn, zipStream, New Byte(4095) {})
    zipStream.CloseEntry()

    zipStream.IsStreamOwner = False		' False stops the Close also Closing the underlying stream.
    zipStream.Close()			' Must finish the ZipOutputStream before using outputMemStream.
    outputMemStream.Position = 0
    Return outputMemStream

    ' Alternative outputs:
    ' ToArray is the cleaner and easiest to use correctly with the penalty of duplicating allocated memory.
    Dim byteArrayOut As Byte() = outputMemStream.ToArray()

    ' GetBuffer returns a raw buffer raw and so you need to account for the true length yourself.
    Dim byteArrayOut As Byte() = outputMemStream.GetBuffer()
    Dim len As Long = outputMemStream.Length
End Function