C++ Primer 学习笔记 第十五章面向对象程序设计

527 类的继承和函数绑定

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    string isbn() const{
        return "hello world";
    };
    // virtual function, will be rewrite
    virtual double net_price(size_t n) const{
        return n;
    }
};

// inherit Quote
class Bulk_quote:public Quote{
public:
    // rewrite net_price
    double net_price(size_t n) const override{
        return n/2;
    }
};

double print_total(ostream &os, const Quote &item, size_t n){
    double ret = item.net_price(n);
    os << "ISBN: " << item.isbn() << " # sold: " << n << " total due: " << ret << endl;
    return ret;
}


int main() {
    Quote basic;
    Bulk_quote bulk;
    print_total(cout, basic, 20); // ISBN: hello world # sold: 20 total due: 20
    print_total(cout, bulk, 20); // ISBN: hello world # sold: 20 total due: 10

}

529 基类和派生类

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string&, double, size_t, double){};
    double net_price(size_t) const override{return discount;};

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    cout << basic.isbn() << endl;

    Bulk_quote bulk("rgd", 10, 3, 10);
    bulk.isbn()

}

530 派生类对象及派生类向基类转换

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string&, double, size_t, double){};
    double net_price(size_t) const override{return discount;};

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    cout << basic.isbn() << endl;

    Bulk_quote bulk("rgd", 10, 3, 10);

    Quote *p = &basic;
    // 派生类对象转基类
    p = &bulk;
    Quote &r = bulk;

}

531 派生类的构造函数

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t) const override{return price*discount;};

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    cout << basic.isbn() << endl;

    Bulk_quote bulk("rgd", 20, 3, 0.8);

    cout << bulk.isbn() << " " << bulk.net_price(5) << endl; // 16


}

531 派生类使用基类成员

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t) const override;

private:
    size_t min_qty = 0;
    double discount = 0.0;
};

double Bulk_quote::net_price(size_t cnt) const {
    if (cnt>=min_qty){
        return cnt*(1-discount)*price;
    } else{
        return cnt*price;
    }
}


int main() {
    Quote basic("avc", 20);
    cout << basic.isbn() << endl;

    Bulk_quote bulk("rgd", 20, 3, 0.2);

    cout << bulk.isbn() << " " << bulk.net_price(5) << endl; // 80


}

532 继承与静态成员

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    static void statmem();
};

class Derived:public Base{
    void f(const Derived&);
};


void Derived::f(const Derived &derived_obj) {
    Base::statmem();
    Derived::statmem();
    derived_obj.statmem();
    statmem(); 
    
}



int main() {
    
}

533 添加final关键字,使得类不能够被继承

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class NoDerived final {

};

class Base{

};

class Last final : Base {

};

// error: marked final
//class Bad:NoDerived{
//
//};

// error: marked final
//class Bad2:Last{
//    
//};


int main() {


}

535 只能从派生类到基类转换

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t) const override{return price*discount;};

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    Bulk_quote bulk("rgd", 20, 3, 0.8);

    Quote base;
    // error: base can not convert into children
//    Bulk_quote* bulkP = &base;
//    Bulk_quote& bulkRef = base;

    Quote *itemP = &bulk; // correct, children can convert into base
//    Bulk_quote *bulkP = itemP; // error


}

535 使用派生类去构造基类部分内容被切割掉

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t) const override{return price*discount;};

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    Bulk_quote bulk("rgd", 20, 3, 0.8);

    Quote item(bulk);
    cout << item.net_price(2); // 2*20

    item = bulk;

}

538 使用override令编译器检查重写函数的形参和虚函数形参是否一样

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


struct B{
    virtual void f1(int) const;
    virtual void f2();
    void v3();
};

struct D1:B{
    void f1(int) const override;
//    void f2(int) override;
};


int main() {


}

538 加了关键字final后不能被重写

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


struct B{
    virtual void f1(int) const;
    virtual void f2();
    void v3();
};

struct D2:B{
    void f1(int) const final;
};

struct D3:D2{
    void f2();
//    error can not override final
//    void f1(int) const;
};




int main() {


}

539 明确指定调用的类方法

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t n) const override{
        return Quote::net_price(n)*discount;
    };

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    Bulk_quote bulk("rgd", 20, 3, 0.8);
    cout << bulk.net_price(10) << endl;

//    double undiscounted = bulk->Quote::net_price(10);
    
}

15.11

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;

    virtual void debug(){
        cout << "bookNo: " << bookNo << " price: " << price << endl;
    };


private:
    string bookNo;
protected:
    double price = 0.0;
};

// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double disc):Quote(book, p), min_qty(qty), discount(disc){};
    double net_price(size_t n) const override{
        return Quote::net_price(n)*discount;
    };
    void debug() override{
        Quote::debug();
        cout << "min_qty: " << min_qty << " discount: " << discount << endl;
    }


private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main() {
    Quote basic("avc", 20);
    Bulk_quote bulk("rgd", 20, 3, 0.8);
    cout << bulk.net_price(10) << endl;

//    double undiscounted = bulk->Quote::net_price(10);

    bulk.debug();

}

541 纯虚以及多级继承

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;

    virtual void debug(){
        cout << "bookNo: " << bookNo << " price: " << price << endl;
    };

private:
    string bookNo;
protected:
    double price = 0.0;
};


class Disc_quote:public Quote{
public:
    Disc_quote()=default;
    Disc_quote(const string& book, double price, size_t qty,
               double disc): Quote(book, price), quantity(qty), discount(disc){};
    double net_price(size_t) const=0;
private:
    size_t quantity = 0;
    double discount = 0;

};


// inherit Quote
class Bulk_quote: public Disc_quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string &book, double price, size_t qty, double disc):Disc_quote(book, price, qty, disc){}
    double net_price(size_t) const override;

    void debug() override{
        Quote::debug();
        cout << "min_qty: " << min_qty << " discount: " << discount << endl;
    }


private:
    size_t min_qty = 0;
    double discount = 0.0;
};





int main() {
    Bulk_quote bulk("rgd", 20, 3, 0.8);
    cout << bulk.net_price(10) << endl;

//    double undiscounted = bulk->Quote::net_price(10);

    bulk.debug();

}

543 protect只能通过派生类成员函数,或者友元里面的派生类形参访问

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
protected:
    int prot_mem;
};


class Sneaky:public Base{
    friend void clobber(Sneaky&);
    friend void clobber(Base&);
    int j;
    void debug(){
        // 通过派生类成员函数访问
        prot_mem = 10;
    }
};

// correct 可以通过派生类形参访问
void clobber(Sneaky &s){
    s.j=s.prot_mem=0;
}

// error 不能通过基类形参访问
//void clobber(Base& b){
//    b.prot_mem=0;
//}



int main() {
    

}

544 受保护继承

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    void pub_mem();

protected:
    int prot_mem;

private:
    char priv_mem;
};


struct Pub_Derv:public Base{
    int f(){return prot_mem;}
    // private number is not accessible
//    char g(){return priv_mem}

};


struct Priv_Derv:private Base{
    int f1() const {return prot_mem;}
};


int main() {

    Pub_Derv d1;
    Priv_Derv d2;
    d1.pub_mem();
    // pub_mem() not accessible because of private Base in declaration of Priv_Derv
    // struct Priv_Derv:private Base
//    d2.pub_mem();


}

545 友元不能继承

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
friend class Pal;
protected:
    int prot_num = 1;

private:
    int priv = 1;
};


class Sneaky:public Base{
protected:
    int j;
};

class Pal{
public:
    int f(Base b){return b.prot_num;};
    // error Pal is not friend of Sneaky
//    int f2(Sneaky s) {return s.j;};
    int f3(Sneaky s){return s.prot_num;};

};


//class D2:public Pal{
//public:
//    int mem(Base b){
//        return b.prot_mem;
//    }
//};


int main() {


}

546 using关键字改变private继承的可访问性

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    size_t size() const{return n;}
protected:
    size_t n;

private:
    size_t priv;
};

class Derived:private Base{
public:
    using Base::size;
protected:
    using Base::n;
// error using is not useless for private number
//private:
//    using Base::priv

};


int main() {


}

15.18-15.19

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    void pub_mem();

protected:
    int prot_mem=2;

private:
    char priv_mem=4;
};


struct Pub_Derv:public Base{
    int f(){return prot_mem;}
    // private number is not accessible
//    char g(){return priv_mem}

    void memfcn(Base &b){
        b = *this;
    }

};


struct Priv_Derv:private Base{
    int f1() const {return prot_mem;}

    void memfcn(Base &b){
        b = *this;
    }
};




struct Prot_Derv:protected Base{
    int f2() const {return prot_mem;}
    void memfcn(Base &b){
        b = *this;
    }


};


struct Derived_from_public:public Pub_Derv{
    int use_base() {return prot_mem;}


    void memfcn(Base &b){
        b = *this;
    }



};

struct Derived_from_private:public Priv_Derv{
    int use_base(){return 0;};

    void memfcn(Base &b){
        b = *this;
    }
};



int main() {

    Pub_Derv d1;
    Priv_Derv d2;
    Prot_Derv d3;

    Derived_from_public dd1;
    Derived_from_private dd2;


    Base b;

    d1.memfcn(b);
    d2.memfcn(b);
    
}

548 同名变量的处理方法

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


struct Base{
    Base():mem(0){}
protected:
    int mem;

};

struct Derived:Base{
    Derived(int i):mem(i){}
    int get_mum(){return mem;}
    int get_base_mum() {return Base::mem;}

protected:
    int mem;
};



int main() {
    Derived d(42);
    cout << d.get_mum() << endl;
    cout << d.get_base_mum() << endl;
    
}

549 函数名比形参列表优先级更高

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


struct Base{
public:
    int memfcn(){return 42;};
};

struct Derived:Base{
    int memfcn(int){
        return 84;
    }
};



int main() {
    Derived d;
    Base b;
    
    b.memfcn();
    d.memfcn(10);
    
    // error memfcn() in Base is hidden here
//    d.memfcn()
    d.Base::memfcn();

}

550 虚函数与作用域

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    virtual int fcn(){
        return 0;
    };
};

class D1:public Base{
public:
    int fcn(int){
        return 1;
    };
    virtual string f2(){string str = "D1"; return str;};
};

class D2:public D1{
public:
    int fcn(int){return 2;};
    int fcn(){return 2;};
    string f2(){string str = "D2"; return str;};

};


int main() {
    Base bobj; D1 d1obj; D2 d2obj;

    Base *bp1=&bobj, *bp2 = &d1obj, *bp3 = &d2obj;

    cout << bp1->fcn() << endl << bp2->fcn() << endl << bp3->fcn() <<endl; // 0 0 2

    D1 *d1p = &d1obj; D2 *d2p = &d2obj;
//    cout << bp2->f2();
    cout << d1p->f2() << endl << d2p->f2(); // D1 D2

    Base *p1 = &d2obj; D1 *p2 = &d2obj; D2 *p3 = &d2obj;
//    cout << p1->fcn(42); error
    cout << p2->fcn(42) << endl << p3->fcn(42);


}

15.23

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{
public:
    virtual int fcn(){
        return 0;
    };
};

class D1:public Base{
public:
    int fcn(){
        return 1;
    };
    virtual string f2(){string str = "D1"; return str;};
};

class D2:public D1{
public:
    int fcn(int){return 2;};
    int fcn(){return 2;};
    string f2(){string str = "D2"; return str;};

};


int main() {
    Base bobj; D1 d1obj; D2 d2obj;

    Base *bp1=&bobj, *bp2 = &d1obj, *bp3 = &d2obj;

    cout << bp1->fcn() << endl << bp2->fcn() << endl << bp3->fcn() <<endl; // 0 1 2

    D1 *d1p = &d1obj; D2 *d2p = &d2obj;
//    cout << bp2->f2();
    cout << d1p->f2() << endl << d2p->f2(); // D1 D2

    Base *p1 = &d2obj; D1 *p2 = &d2obj; D2 *p3 = &d2obj;
//    cout << p1->fcn(42); error
    cout << "p2->fcn(42)" << endl << p3->fcn(42); //2


}

554 合成拷贝控制的继承

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class B{
public:
    B();
    B(const B&)=delete;
};

class D:public B{
    
};


int main() {
    D d;
    // 拷贝控制函数被删除了,所以不合法
	//D d2(d);
	//D d3(move(d))

}

555 定义派生类的移动构造函数

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{

};

class D:public Base{
public:
//     Base(d) match copy constructor in Base, use d to initialize base
    D(const D& d): Base(d){}
//  可以运行,但是实际没意义,因为新对象中的数据copy了d中的,但是基类使用了默认的构造函数,没有使用d中的数值,显得很奇怪
//    D(const D &d){}

    D(D&& d): Base(move(d)){}
};


int main() {

}

556 派生类的赋值运算符

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{

};

class D:public Base{
public:
//     Base(d) match copy constructor in Base, use d to initialize base
    D(const D& d): Base(d){}
//  可以运行,但是实际没意义,因为新对象中的数据copy了d中的,但是基类使用了默认的构造函数,没有使用d中的数值,显得很奇怪
//    D(const D &d){}

    D(D&& d): Base(move(d)){}

    D &D::operator=(const D &rhs){
        Base::operator=(rhs);
        return *this;
    };

};


int main() {

}

556 派生类析构函数

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Base{

};

class D:public Base{
public:
//     Base(d) match copy constructor in Base, use d to initialize base
    D(const D& d): Base(d){}
//  可以运行,但是实际没意义,因为新对象中的数据copy了d中的,但是基类使用了默认的构造函数,没有使用d中的数值,显得很奇怪
//    D(const D &d){}

    D(D&& d): Base(move(d)){}

    D &D::operator=(const D &rhs){
        Base::operator=(rhs);
        return *this;
    };

    ~D(){}
};


int main() {

}

557 继承基类的构造函数

构造函数默认是,不能被继承,如果需要继承构造函数,需要用到using关键字

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;

    virtual void debug(){
        cout << "bookNo: " << bookNo << " price: " << price << endl;
    };

private:
    string bookNo;
protected:
    double price = 0.0;
};


class Disc_quote:public Quote{
public:
    Disc_quote()=default;
    Disc_quote(const string& book, double price, size_t qty,
               double disc): Quote(book, price), quantity(qty), discount(disc){};
    double net_price(size_t) const=0;
private:
    size_t quantity = 0;
    double discount = 0;

};


// inherit Quote
class Bulk_quote: public Disc_quote{
public:
    Bulk_quote() = default;
//    Bulk_quote(const string &book, double price, size_t qty, double disc):Disc_quote(book, price, qty, disc){}
	// 用using, 继承构造函数,等于上面那一句
    using Disc_quote::Disc_quote;

    double net_price(size_t) const override;

    void debug() override{
        Quote::debug();
        cout << "min_qty: " << min_qty << " discount: " << discount << endl;
    }


private:
    size_t min_qty = 0;
    double discount = 0.0;
};

558 把派生类存入基类的容器中

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;
private:
    string bookNo;
protected:
    double price = 0.0;
};



// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double dis): Quote(book, p), min_qty(qty), discount(dis){}
    double net_price(size_t n) const override{
        return n*price*discount;
    };

private:
    size_t min_qty = 0;
    double discount = 0.0;
};


int main(){
    vector<Quote> basket;
    basket.push_back(Quote("abc", 10));
    basket.push_back(Bulk_quote("eft", 10, 3, 0.8));
    // call net_price() in Quote but not Disc_quote
    cout << basket.back().net_price(2) << endl; // 20

    vector<shared_ptr<Quote>> basket1;
    basket1.push_back(make_shared<Quote>("abc", 10));
    basket1.push_back(make_shared<Bulk_quote>("efg", 10, 3, 0.8));
    cout << basket1.back()->net_price(2) << endl; // 16

    return 0;
}

561 模拟虚拷贝

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
#include <set>
using namespace std;


class Quote{
public:
    Quote() = default;
    Quote(const string &book, double sales_price):bookNo(book), price(sales_price){}
    string isbn() const {return bookNo;};
    virtual double net_price(size_t n) const{return n*price;}
    virtual ~Quote()=default;

    virtual Quote* clone() const & {return new Quote(*this);};
    virtual Quote* clone() const && {return new Quote(move(*this));};

private:
    string bookNo;
protected:
    double price = 0.0;
};



// inherit Quote
class Bulk_quote: public Quote{
public:
    Bulk_quote() = default;
    Bulk_quote(const string& book, double p, size_t qty, double dis): Quote(book, p), min_qty(qty), discount(dis){}
    double net_price(size_t n) const override{
        return n*price*discount;
    };

    Bulk_quote* clone() const &{return new Bulk_quote(*this);};
    Bulk_quote* clone() && {return new Bulk_quote(move(*this));};
private:
    size_t min_qty = 0;
    double discount = 0.0;
};


class Basket{
public:
    void add_item(const Quote& sale){
        items.insert(shared_ptr<Quote>(sale.clone()));
    }
    void add_item(Quote&& sale){
        items.insert(shared_ptr<Quote>(move(sale).clone()));
    }

    double total_receipt(ostream&) const;

private:
    static bool compare(const shared_ptr<Quote> &lhs, const shared_ptr<Quote> &rhs){
        return lhs->isbn() < rhs->isbn();
    }
    multiset<shared_ptr<Quote>, decltype(compare)*> items{compare};
};



int main(){


    return 0;
}

562-574 类的完整例子,(未成功运行)

#include <iostream>
#include <vector>
#include <string>
#include <list>
#include <iterator>
#include <memory>
#include <fstream>
#include <algorithm>
#include <functional>
#include <map>
#include <set>
#include <sstream>
using namespace std;
using line_no = vector<string>::size_type;


class QueryResult{
    friend ostream& print(ostream&, const QueryResult&);

public:
    QueryResult(string s,
                shared_ptr<set<line_no>> p,
    shared_ptr<vector<string>> f): sought(s), lines(p), file(f){}
private:
    string sought;
    shared_ptr<set<line_no>> lines;
    shared_ptr<vector<string>> file;
};

string make_plural(size_t num, const string& input, const string& suffix){
    return (num > 1)? input+suffix:input;
}

ostream &print(ostream & os, const QueryResult &qr){
    os << qr.sought << " occurs " << qr.lines->size() << " " << make_plural(qr.lines->size(), "time", "s") << endl;
    for (auto  num:*qr.lines){
        os << "t(line " << num+1 << ") " << *(qr.file->begin()+num) << endl;
    }
    return os;
}

class TextQuery{
public:
    TextQuery(ifstream &);
    QueryResult query(const string&) const;

private:
    shared_ptr<vector<string>> file;
    map<string, shared_ptr<set<line_no>>> wm;
};
TextQuery::TextQuery(ifstream &is): file(new vector<string>) {
    string text;
    while (getline(is, text)){
        file->push_back(text);
        int n = file->size() - 1;
        istringstream line(text);
        string word;
        while (line>>word){
            auto &lines = wm[word];
            if (!lines)
                lines.reset(new set<line_no>);
            lines->insert(n);
        }
    }
}
QueryResult TextQuery::query(const string &sought) const {
    static shared_ptr<set<line_no>> nodata(new set<line_no>);
    auto loc = wm.find(sought);
    if (loc==wm.end()){
        return QueryResult(sought, nodata, file);
    } else{
        return QueryResult(sought, loc->second, file);
    }
}



class Query_base{
    friend class Query;
protected:
//    using line_no = TextQuery::line_no;
    virtual ~Query_base() = default;
private:
    virtual QueryResult eval(const TextQuery&) const=0;
    virtual string rep() const=0;
};


class Query{
    friend Query operator~(const Query&);
    friend Query operator|(const Query&, const Query&);
    friend Query operator&(const Query&, const Query&);
public:
    Query(const string&);
    QueryResult eval(const TextQuery&t) const{
        return q->eval(t);
    }
    string rep() const {return q->rep();}

private:
    Query(shared_ptr<Query_base> query):q(query){}
    shared_ptr<Query_base> q;
};

ostream & operator<<(ostream &os, const Query &query){
    return os<<query.rep();
}

class WordQuery:public Query_base{
    friend class Query;
    WordQuery(const string &s):query_word(s){}
    QueryResult eval(const TextQuery &t) const {
        return t.query(query_word);
    }
    string rep() const {return query_word;}
    string query_word;
};

inline Query::Query(const string &s):q(new WordQuery(s)){}

class NotQuery:public Query_base{
    friend Query operator~(const Query&);
    NotQuery(const Query &q):query(q){}
    string rep() const {return "~(" + query.rep() + ")";}
    QueryResult eval(const TextQuery&) const;
    Query query;
};
inline Query operator~(const Query &operand){
    return shared_ptr<Query_base>(new NotQuery(operand));
}

class BinaryQuery:public Query_base{
protected:
    BinaryQuery(const Query &l, const Query &r, string s):lhs(l), rhs(r), opSym(s){}
    string rep() const{
        return "(" + lhs.rep() + " " + opSym + " " + rhs.rep() + ")";
    }
    Query lhs, rhs;
    string opSym;
};

class AndQuery:public BinaryQuery{
    friend Query operator&(const Query&, const Query&);
    AndQuery(const Query &left, const Query &right): BinaryQuery(left, right, "&"){}
    QueryResult eval(const TextQuery&) const;
};
inline Query operator&(const Query &lhs, const Query &rhs){
    return shared_ptr<Query_base>(new AndQuery(lhs, rhs));
}

class OrQuery:public BinaryQuery{
    friend Query operator|(const Query&, const Query&);
    OrQuery(const Query &left, const Query &right): BinaryQuery(left, right, "|"){}
    QueryResult eval(const TextQuery&) const;
};
inline Query operator|(const Query &lhs, const Query &rhs){
    return shared_ptr<Query_base>(new OrQuery(lhs, rhs));
}


QueryResult OrQuery::eval(const TextQuery & text) const {
    auto right = rhs.eval(text), left = lhs.eval(text);
    auto ret_lines = make_shared<set<line_no>>(left.begin(), left.end());
    ret_lines->insert(right.begin(), right.end());
    return QueryResult(rep(), ret_lines, left.get_file());

}

QueryResult AndQuery::eval(const TextQuery &text) const {
    auto left=lhs.eval(text),right=rhs.eval(text);
    auto ret_lines = make_shared<set<line_no>>();
    set_intersection(left.begin(), left.end(),
                     right.begin(), right.end(),
                     inserter(*ret_lines, ret_lines->begin()));
    return QueryResult(rep(), ret_lines,left.get_file());
}

QueryResult NotQuery::eval(const TextQuery &text) const {
    auto result = query.eval(text);
    auto ret_lines = make_shared<set<line_no>>();
    auto beg = result.begin(), end = result.end();
    auto sz = result.get_file()->size();
    for (size_t n=0; n!=sz; ++n){
        if (beg==end || *beg!=n){
            ret_lines->insert(n);
        }else if(beg!=end){
            ++beg;
        }
    }
    return QueryResult(rep(), ret_lines, result.get_file());
}

int main(){



}

最后

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