【足迹C++primer】45、拷贝控制示例

拷贝控制示例

那么接下来尽情欣赏这个案例吧！！！

/*** 功能:拷贝控制示例* 时间:2014年7月14日10:57:39* 作者:cutter_point*/#include<iostream>#include<set>#include<vector>#include<string>using namespace std;class Folder;/**Message类*/class Message{    friend void swap(Message&, Message&);    friend class Folder;public:    //folders被隐式初始化为空集合    explicit Message(const string &str=""):contents(str){}    //拷贝控制成员，用来管理指向本Message的指针    Message(const Message&);        //拷贝构造函数    Message& operator=(const Message&); //拷贝赋值运算符    ~Message();                     //析构函数    //从给定的Folder中添加/删除本Message    void save(Folder&);    void remove(Folder&);    //显示有几个Message对象    void show();private:    string contents;        //实际消息文本    set<Folder*> folders;   //包含本Message的folder    //拷贝构造函数，拷贝赋值运算符合析构函数所使用的工具函数    //将本message添加到指向参数的folder中    void add_to_Folders(const Message&);    //从folders中的每个Folder中删除本Message    void remove_from_Folders();    //向folders添加和删除    void addFldr(Folder *f){folders.insert(f);}    void remFldr(Folder *f){folders.erase(f);}};/**Folder类*/class Folder{    friend void swap(Message&, Message&);    friend class Message;public:    //构造函数    Folder()=default;    //拷贝构造函数    Folder(const Folder&);    //拷贝赋值运算符    Folder & operator=(const Folder&);    //析构函数    ~Folder();    //对应的save和remove函数    void save(Message&);    void remove(Message&);    //显示有几个Message    void show();private:    set<Message*> msgs;         //用来保存当前Folder保存的各种Message对象    //拷贝构造函数，拷贝赋值运算符合析构函数所使用的工具函数    //将本message添加到指向参数的folder中    void add_to_Message(const Folder&);    //从folders中的每个Folder中删除本Message    void remove_from_Message();    void addMsg(Message *m){msgs.insert(m);}       //添加一个对象    void remMsg(Message *m){msgs.erase(m);}};/**展示有几个set成员*/void Message::show(){    cout<<"folders的个数有:"<<folders.size()<<endl;}void Folder::show(){    cout<<"msgs的个数有:"<<msgs.size()<<endl;}/**save和remove成员*/void Folder::save(Message &m){    msgs.insert(&m);    m.addFldr(this);}void Message::save(Folder &f){    folders.insert(&f);     //将给定Folder添加到我们的Folder列表中    f.addMsg(this);         //将本Message添加到f的Message中}void Folder::remove(Message &m){    msgs.erase(&m);    m.remFldr(this);}void Message::remove(Folder &f){    folders.erase(&f);      //将给定Folder从我们的Folder列表中删除    f.remMsg(this);         //将本Message从f的Message中删除}/**Message类的拷贝控制成员*///将本Message添加到指向m的Folder中void Message::add_to_Folders(const Message &m){    for(auto f : m.folders)     //对每个包含m的set的folder        f->addMsg(this);        //向Folder添加一个指向本Message的指针}Message::Message(const Message &m):contents(m.contents), folders(m.folders){    add_to_Folders(m);}/**Message的析构函数*///对应的Folder中删除本Message,这个是析构函数要用到的工具函数void Message::remove_from_Folders(){    for(auto f : folders)        f->remMsg(this);        //从该Folder中删除本Message}Message::~Message(){    remove_from_Folders();}/**Message的拷贝赋值运算符*/Message& Message::operator=(const Message &rhs){    //先把本对象的全部指针清空，准备接受右边的赋值    remove_from_Folders();      //更新已有的Folder    contents=rhs.contents;    folders=rhs.folders;    //将本文本添加发哦相应的Folders中    add_to_Folders(rhs);    return *this;}/**Message的swap函数*/void swap(Message &lhs, Message &rhs){    using std::swap;    //在本例中严格来说不需要，但是这是一个好习惯    //将每个相应的消息从原来的Folder中删除    for(auto f : lhs.folders)        f->remMsg(&lhs);    for(auto f : rhs.folders)        f->remMsg(&rhs);    //交换相应的数据    swap(lhs.folders, rhs.folders); //swap(set&, set&)    swap(lhs.contents, rhs.contents);   //swap(string&, string&)    //将每个Message的指针添加到它的（新）Folder中,已经交换了    for(auto f : lhs.folders)        f->addMsg(&lhs);    for(auto f : rhs.folders)        f->addMsg(&rhs);}/**Folder的拷贝构造，拷贝赋值运算符，析构函数定义*/void Folder::add_to_Message(const Folder &f){    for(auto m : f.msgs)        m->addFldr(this);}Folder::Folder(const Folder &f):msgs(f.msgs){    add_to_Message(f);}//拷贝赋值运算符void remove_from_Messagevoid Folder::remove_from_Message(){    for(auto m : msgs)       //清除全部指针        m->remFldr(this);}Folder& Folder::operator=(const Folder &rhs){    //先把本对象的所有指针清空    remove_from_Message();    msgs=rhs.msgs;    //赋值完成后添加到那些message中    add_to_Message(rhs);    return *this;}//析构函数Folder::~Folder(){    remove_from_Message();}int main(){    string s1("cutter_point1");string s2("cutter_point2");string s3("cutter_point3");string s4("cutter_point4");string s5("cutter_point5");string s6("cutter_point6");// all new messages, no copies yetMessage m1(s1);Message m2(s2);Message m3(s3);Message m4(s4);Message m5(s5);Message m6(s6);Folder f1;Folder f2;m1.save(f1); m3.save(f1); m5.save(f1);m1.save(f2);m2.save(f2); m4.save(f2); m6.save(f2);// create some copiesMessage c1(m1);Message c2(m2), c4(m4), c6(m6);// now some assignmentsm2 = m3;m4 = m5;m6 = m3;m1 = m5;// finally, self-assignmentm2 = m2;m1 = m1;vector<Message> vm;cout << "capacity（初始vm容纳量）: " << vm.capacity() << endl;vm.push_back(m1);cout << "capacity（添加m1后vm容纳量）: " << vm.capacity() << endl;vm.push_back(m2);cout << "capacity（添加m2后vm容纳量）: " << vm.capacity() << endl;vm.push_back(m3);cout << "capacity（添加m3后vm容纳量）: " << vm.capacity() << endl;vm.push_back(m4);cout << "capacity（添加m4后vm容纳量）: " << vm.capacity() << endl;vm.push_back(m5);cout << "capacity（添加m5后vm容纳量）: " << vm.capacity() << endl;vm.push_back(m6);cout << "capacity（添加m6后vm容纳量）: " << vm.capacity() << endl;vector<Folder> vf;cout << "capacity（初始vf容纳量）: " << vf.capacity() << endl;vf.push_back(f1);cout << "capacity（添加f1后vf容纳量）: " << vf.capacity() << endl;vf.push_back(f2);cout << "capacity（添加f2后vf容纳量）: " << vf.capacity() << endl;vf.push_back(Folder(f1));cout << "capacity（再添加f1后vf容纳量）: " << vf.capacity() << endl;vf.push_back(Folder(f2));cout << "capacity（再添加f2后vf容纳量）: " << vf.capacity() << endl;vf.push_back(Folder());cout << "capacity（再添加空Folder后vf容纳量）: " << vf.capacity() << endl;Folder f3;f3.save(m6);vf.push_back(f3);cout << "capacity（再添加空f3后vf容纳量）: " << vf.capacity() << endl;cout<<"m1到m6中folders的个数："<<endl;m1.show(); m2.show(); m3.show();m4.show(); m5.show(); m6.show();cout<<"f1到f3中Message的个数："<<endl;f1.show(); f2.show(); f3.show();cout<<"c1,c2,c4,c6中folders的个数："<<endl;c1.show(); c2.show();c4.show(); c6.show();    return 0;}

这个我运行出了结果，给大家看一看！！