compilation error: boost/serialization/access.hpp(123): error: no default constructor exists for class "A" Do I need to change anything in the class at all? Also what are the meanings of these compilation error: boost/serialization/access.hpp(109) error: incomplete type is not allowed. boost/serialization/access.hpp(109) error: expression must have class type __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com