title: Why is compressed then uncompressed stream of different length
body: <p>I'm using the SevenZipSharp library to compress and then uncompress a MemoryStream which contains a simple serialized object. However, the compressed and decompressed streams are of different length. </p>
  
  <p>From the code run below I get </p>
  
  <p>Input length: 174
  Output length: 338</p>
  
  <p>(the SevenZipSharp dll is included as a reference and the 7z.dll is included in the project output)</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.IO;
  using System.Runtime.Serialization.Formatters.Binary;
  
  namespace DataTransmission {
  class Program {
      static void Main(string[] args)
      {
  
          SevenZip.SevenZipCompressor compressor = new SevenZip.SevenZipCompressor();
          //compressor.CompressionMethod = SevenZip.CompressionMethod.Lzma2;
          //compressor.CompressionLevel = SevenZip.CompressionLevel.Normal;
  
          MemoryStream inputStream = new MemoryStream();
  
          Person me = new Person("John", "Smith");
          BinaryFormatter formatter = new BinaryFormatter();
          formatter.Serialize(inputStream, me);
  
          Int32 inputStreamLength = (Int32)inputStream.Length;
  
          MemoryStream outputStream = new MemoryStream();
  
          compressor.CompressStream(inputStream, outputStream);
          SevenZip.SevenZipExtractor decompressor = new SevenZip.SevenZipExtractor(outputStream);
          decompressor.ExtractFile(0, outputStream);
          Int32 outputStreamLength = (Int32)outputStream.Length;
  
  
          Console.WriteLine("Input length: {0}", inputStreamLength);
          Console.WriteLine("Output length: {0}", outputStreamLength);
  
          Console.ReadLine();
      }
  }
  
  [Serializable]
  public class Person {
      public string firstName;
      public string lastName;
  
      public Person(string fname, string lname) {
          firstName = fname;
          lastName = lname;
      }
  }
  
  }
  </code></pre>
  
  <p>Can anyone help me with why this may be?</p>
  
  <p>Thanks,</p>