If the data to compress is not a byte array, it will need to be converted into a byte array before it can be compressed. This can be done, in the case of a string, using the System.Text.Encoding.GetBytes(System.Char[]) method of the System.Text.Encoding class.
The compression level only applies to the Deflated and Deflated64 compression methods. It does not apply to the BZip2, BWT, or PPMd compression methods.
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2