I am using the BinaryFormatter to serialize an object of class X to a file. Then another program reads in the file and deserialize back into the object. If I put the declaration of class X in a separate cs file and compile it to a DLL, include it as a reference in both programs, it works fine. But there is a DLL file needed at runtime for each program.

If I merely include the exactly same class X code in each program, deserialization comes with "Unable to cast object of type 'namespace.X' to type namespace.X'" I suppose this is to be expected as there is no way from the source code to uniquely identify the class.

How can I make deserialization work without having to include a separate DLL file at runtime?

Thanks.

You don't (without a lot of hassle). Part of the Type name is the assembly it came from, so the Type in your two applications is different.

The easiest thing to do (and I'd argue most proper) is to have a shared assembly for your shared Types (as you've already discovered).

The next easiest thing to do is use XML serialization instead. If you are adamant on having your types hosted in two different assemblies, you can accomplish this easier with XML serialization.

Finally, for binary serialization, look into ISerializationSurrogate. Basically you'd have to forego automatic binary serialization in favor of ISerializable, but it's a way to do it.

You don't (without a lot of hassle). Part of the Type name is the assembly it came from, so the Type in your two applications is different.

The easiest thing to do (and I'd argue most proper) is to have a shared assembly for your shared Types (as you've already discovered).

The next easiest thing to do is use XML serialization instead. If you are adamant on having your types hosted in two different assemblies, you can accomplish this easier with XML serialization.

Finally, for binary serialization, look into ISerializationSurrogate. Basically you'd have to forego automatic binary serialization in favor of ISerializable, but it's a way to do it.