消息类和消息所在的目录类....

#ifndef MESSAGE_H#define MESSAGE_H#include <iostream>#include <set>class Message;class Folder{public:Folder(){}Folder(const Folder& f);Folder& operator=(const Folder& rhs);~Folder();    void save(Message& m);void remove(Message& m);void remMes(Message* m);    void addMes(Message* m);private:std::set<Message*> messages;void put_folder_in_msgs(const std::set<Message*>& rhs);    void rem_folder_from_msgs();};class Message{public:Message(const std::string& str=""):contents(str){}Message::Message(const Message& rhs);Message& operator=(const Message& rhs);~Message();void save(Folder& f);void remove(Folder& f);void addfolder(Folder* f);void remfolder(Folder* f);private:std::string contents;std::set<Folder*> folders;void put_msg_in_Folders(const std::set<Folder*>& rhs);void remove_msg_form_folders();};    Folder::Folder(const Folder& f):messages(f.messages){}Folder& Folder::operator=(const Folder& rhs){if (&rhs!=this){rem_folder_from_msgs();messages=rhs.messages;put_folder_in_msgs(rhs.messages);}return *this;}Folder::~Folder(){rem_folder_from_msgs();}void Folder::save(Message& m){addMes(&m);m.addfolder(this);}void Folder::remove(Message& m){remMes(&m);m.remfolder(this);}void Folder::remMes(Message* m){messages.insert(m);}void Folder::addMes(Message* m){messages.erase(m);}void Folder::put_folder_in_msgs(const std::set<Message*>& rhs){for (std::set<Message*>::const_iterator it=rhs.begin();it!=rhs.end();it++){(*it)->addfolder(this);}}void Folder::rem_folder_from_msgs(){for (std::set<Message*>::const_iterator it=messages.begin();it!=messages.end();it++){(*it)->remfolder(this);}}Message::Message(const Message& rhs):contents(rhs.contents),folders(rhs.folders){put_msg_in_Folders(folders);}Message& Message::operator=(const Message& rhs){if (&rhs!=this){remove_msg_form_folders();contents=rhs.contents;folders=rhs.folders;put_msg_in_Folders(rhs.folders);}return *this;}Message::~Message(){remove_msg_form_folders();}void Message::save(Folder& f){addfolder(&f);f.addMes(this);}void Message::remove(Folder& f){remfolder(&f);        f.remMes(this);}void Message::addfolder(Folder* f){folders.insert(f);}void Message::remfolder(Folder* f){folders.erase(f);}void Message::put_msg_in_Folders(const std::set<Folder*>& rhs){for (std::set<Folder*>::const_iterator beg=rhs.begin();beg!=rhs.end();beg++){(*beg)->addMes(this);}}void Message::remove_msg_form_folders(){for (std::set<Folder*>::const_iterator beg=folders.begin();beg!=folders.end();beg++){(*beg)->remMes(this);}}#endif