Using ObjectARX (C++) for AutoCAD 2010, can AutoCAD entities be serialized?

We need to save the serialized entity in a field in a database (Oracle, PostgreSQL, etc., not AcDbDatabase). It'OK if you show me how to save them in disk, something like this:

AcDbEntity * entity;
...
std::ofstream ofs("c:\\filename.fil", std::ios::binary);
ofs.write((char *)(entity), sizeof(entity));
ofs.close();

Thanks