#include <iostream>

#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/vector.hpp>
#include <fstream>

class A
{
  public:
  A(){}

  private:
  //Serialization tasks
  friend class boost::serialization::access;
  template<class Archive>
  void serialize(Archive & , const unsigned int )
  {

  }
};

int main()
{
   A eig;
   //std::cout <<eig.size()<<std::endl;
  std::ofstream of("file.txt");
  {
    boost::archive::text_oarchive oa(of);
    oa << eig;
  }
  of.close();
  std::ifstream ifs("file.txt");
  {
    boost::archive::text_iarchive ia(ifs);
    ia >> eig;
  }
  //std::cout <<eig.size()<<std::endl;

   return 0;
}

In function 'void boost::archive::save(Archive&, T&) [with Archive = boost::archive::text_oarchive, T = A]':
/usr/include/boost/archive/detail/common_oarchive.hpp:62:   instantiated from 'void boost::archive::detail::common_oarchive<Archive>::save_override(T&, int) [with T = A, Archive = boost::archive::text_oarchive]'
/usr/include/boost/archive/basic_text_oarchive.hpp:75:   instantiated from 'void boost::archive::basic_text_oarchive<Archive>::save_override(T&, int) [with T = A, Archive = boost::archive::text_oarchive]'
/usr/include/boost/archive/detail/interface_oarchive.hpp:79:   instantiated from 'Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = A, Archive = boost::archive::text_oarchive]'
t.cpp:31:   instantiated from here
Line 565: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' 
compilation terminated due to -Wfatal-errors.