I was doing some comparison between BinaryFormatter and protobuf-net serializer and was quite pleased with what I found, but what was strange is that protobuf-net managed to serialize the objects into a smaller byte array than what I would get if I just wrote the value of every property into an array of bytes without any metadata.
I know protobuf-net supports string interning if you set AsReference to true, but I'm not doing that in this case, so does protobuf-net provide some compression by default?
Here's some code you can run to see for yourself:
var simpleObject = new SimpleObject
                       {
                           Id = 10,
                           Name = "Yan",
                           Address = "Planet Earth",
                           Scores = Enumerable.Range(1, 10).ToList()
                       };
using (var memStream = new MemoryStream())
{
    var binaryWriter = new BinaryWriter(memStream);
    // 4 bytes for int
    binaryWriter.Write(simpleObject.Id);      
    // 3 bytes + 1 more for string termination
    binaryWriter.Write(simpleObject.Name);    
    // 12  bytes + 1 more for string termination
    binaryWriter.Write(simpleObject.Address); 
    // 40 bytes for 10 ints
    simpleObject.Scores.ForEach(binaryWriter.Write); 
    // 61 bytes, which is what I expect
    Console.WriteLine("BinaryWriter wrote [{0}] bytes",
      memStream.ToArray().Count());
}
using (var memStream = new MemoryStream())
{
    ProtoBuf.Serializer.Serialize(memStream, simpleObject);
    // 41 bytes!
    Console.WriteLine("Protobuf serialize wrote [{0}] bytes",
      memStream.ToArray().Count());
}
EDIT: forgot to add, the SimpleObject class looks like this:
[Serializable]
[DataContract]
public class SimpleObject
{
    [DataMember(Order = 1)]
    public int Id { get; set; }
    [DataMember(Order = 2)]
    public string Name { get; set; }
    [DataMember(Order = 3)]
    public string Address { get; set; }
    [DataMember(Order = 4)]
    public List<int> Scores { get; set; }
}
 
     
     
     
    