Compress a byte[] array

[Levi]

Hello,
 
    I tried to compress a byte array in C# using Zip Library, but it seems I a missing something because every time I call compress sending a byte array parameter, I cannot decompress it correctly please see code as follows to compress

private string Compress(byte[] data)
       {
           MemoryStream memoryStream = new MemoryStream();
           ZipCompression method = ZipCompression.Default;
           ZipOutputStream zipOutputStream = new ZipOutputStream(memoryStream, method);
           StreamWriter writer = new StreamWriter(zipOutputStream);

           writer.Write(data);
           writer.Flush();
           return Convert.ToBase64String(memoryStream.ToArray());
       }

and the following is how I decompress it back and the function will return byte array as follows:

private byte[] UnCompress(string str)
        {
            MemoryStream memoryStream = new MemoryStream(Convert.FromBase64String(str));
            ZipInputStream input = new ZipInputStream(memoryStream);
            StreamReader reader = new StreamReader(input);

            return memoryStream.ToArray();

        }

Thanks,

Levi

[Viktor Tsvetkov]

Hi Levi,

You simply need to use the defined StreamReader object in order to read from the ZipInputStream (opposite to what you do with the ZipOutputStream - you write data into it) as follows: reader.ReadToEnd(); and then if you need convert the string to byte array again.

Kind regards,
Viktor Tsvetkov
the Telerik team

[B]

Hi,

Maybe a bit late reaction, but here is what I came up with.

The compress/decompress code works on both Silverlight client (Silverlight dll) and server (WPF dll).

Regards,

Bayram

public static byte[] Compress(string text)
{
    using (MemoryStream memoryStream = new MemoryStream())
    {
        using (ZipOutputStream zipOutputStream = new ZipOutputStream(memoryStream, ZipCompression.Default))
        {
            using (StreamWriter streamWriter = new StreamWriter(zipOutputStream))
            {
                streamWriter.Write(text);
                streamWriter.Flush();
                byte[] bytes = memoryStream.ToArray();
                return bytes;
            }
        }
    }
}
public static string Decompress(byte[] data)
{
    using (MemoryStream memoryStream = new MemoryStream(data))
    {
        using (ZipInputStream zipInputStream = new ZipInputStream(memoryStream))
        {
            using (StreamReader streamReader = new StreamReader(zipInputStream, new System.Text.UTF8Encoding()))
            {
                string text = streamReader.ReadToEnd();
                return text;
            }
        }
    }
}

Examples of how to use them:

// From XElement to compressed byte[]
XElement groupXml = DefinitionSelector.GetGroupDefinition(groupName, definitionFile);
string text = groupXml.ToString();
byte[] c = PowerUtils.Compress(text);

// From compressed byte[] to XElement
string text = PowerUtils.Decompress(data);
XElement groupXml = XElement.Parse(text);
DefinitionSelector.PutGroupDefinition(groupName, groupXml);

[B]

Changed this code to work with the new version 2014 Q1

public static byte[] Compress(string text)
{
    using (MemoryStream memoryStream = new MemoryStream())
    {
        using (ZipOutputStream zipOutputStream = new ZipOutputStream(memoryStream, ZipCompression.Deflated))
        {
            using (StreamWriter streamWriter = new StreamWriter(zipOutputStream))
            {
                streamWriter.Write(text);
                //streamWriter.Flush();
            }
            byte[] bytes = memoryStream.ToArray();
            return bytes;
        }
    }
}
public static string Decompress(byte[] data)
{
    using (MemoryStream memoryStream = new MemoryStream(data))
    {
        using (ZipInputStream zipInputStream = new ZipInputStream(memoryStream))
        {
            using (StreamReader streamReader = new StreamReader(zipInputStream, new System.Text.UTF8Encoding()))
            {
                string text = streamReader.ReadToEnd();
                return text;
            }
        }
    }
}