c++ - Serialize a class with a Qlist of custom classes as member (using QDataStream) -

i'm trying serialize class lesson(my custom class[i removed setters]), includes qlist(question custom class). during test serialization sigsegv(segmentation fault) when deserializing object of qlist inside class lesson.

upd1: serialized qlist* , changed qlist, sigsegv still appears.

class lesson {  public: lesson(); lesson(qstring, qstring, qlist<question>);  qstring getname() const; qstring gettext() const; qlist<question>* gettest() const;  friend qdatastream &operator<<(qdatastream &out, const lesson &l){     out << l.getname() << l.gettext();     out << l.gettest();     return out; }  friend qdatastream &operator>>(qdatastream &in, lesson &l){     qstring name;     qstring text;     qlist<question> t;     in >> name >> text >> t;     l = lesson(name, text, t);     return in; }   friend qdatastream &operator<<(qdatastream &out, const lesson *&l){     out << l->getname() << l->gettext();     return out; }  friend qdatastream &operator>>(qdatastream &in, lesson *&l){     qstring name;     qstring text;     qlist<question> test;     in >> name >> text;// >> test;     l = new lesson(name, text, test);     return in; }   private: qstring text; qlist <question>* test_; qstring name;    }; 

//class question starts here

class question {  public: explicit question(qstring, qlist<qstring>, int type, qlist<int> ans); question();  friend qdatastream &operator <<(qdatastream& out, const question &q){     out << q.type << q.questtext << q.variants << q.answer;     return out; }  friend qdatastream &operator >>(qdatastream& in, question &q){     int type;     qstring questext;     qlist<qstring> vars;     qlist<int>ans;     in >> type >> q >> vars >> ans;     q = question(questext, vars, type, ans);     return in; }  friend qdatastream &operator <<(qdatastream& out, const question *&q){     //out.setbyteorder(qsysinfo::byteorder);     out << q->type << q->questtext << q->variants << q->answer;     return out; }  friend qdatastream &operator >>(qdatastream& in, question *&q){     //in.setbyteorder(qsysinfo::byteorder);     int type;     qstring questext;     qlist<qstring> vars;     qlist<int>ans;     in >> type >> q >> vars >> ans;     q = new question(questext, vars, type, ans);     return in; }  int gettype() const; qstring getquesttext() const; qlist<qstring> getvariants() const; qlist<int> getanswer() const;  signals:  public slots:  private: int type; // see constants.h qstring questtext; qlist<qstring> variants; qlist<int> answer;   }; 

// main.cpp test serialization

int main(int argc, char *argv[]) { qapplication a(argc, argv); core *c = new core; mainwindow w; qobject::connect(&w, signal(sendcheckuservaliditytocore(qstring,qstring)), c,      slot(checkuservalidity(qstring,qstring))); qobject::connect(&w, signal(sendlessontocore(lesson*)), c, slot(savelesson(lesson*))); qobject::connect(&w, signal(requestlessonbyidfromcore(qstring)), c, slot(getlessonbyid(qstring))); qobject::connect(c, signal(returnlessonbyid(lesson*)), &w, signal(returnlessonbyidfromcore(lesson*))); qobject::connect(c, signal(entranceoff()), &w, slot(entranceoff()));  qfile tfile("lessons/tfile.stc"); tfile.open(qiodevice::readwrite); qdatastream inout(&tfile); qlist<question> qlistq; question q; q.setquesttext("qwhy"); qlistq.insert(0, q);  lesson lessont("hello", "welt", qlistq); lesson lessonout; inout << lessont; inout.device()->reset(); inout >> lessonout; qdebug() << lessonout.getname();   return a.exec(); } 

you serialize qlist<question>* , deserialize qlist<question>. change operator<< to:

friend qdatastream &operator<<(qdatastream &out, const lesson &l){     out << name << text << *test_;     return out; }