[Boost-users] Map Binary archive problem May be a bug?

On my phone, so I try my best to describe my problem. std::map myMap; for(int i = 0; i != 30; i++) myMap.insert( make_pair(i,i+1) ); ofstream ofs("test"); binary_oarchive oa(ofs); oa<>myMap; This code will throw an exception "input stream error". But if reducing the size of map like this for(int i = 0;i != 20; i++) It will run successful. Cause I can't figure it out so I seek your help. Look forward to your reply.