实验5

task1

（1）

#pragma once
#include <string>
 
class Publisher {
public:
    Publisher(const std::string &name_ = "");            
    virtual ~Publisher() = default;
public:
    virtual void publish() const = 0;                 
    virtual void use() const = 0;                     
protected:
    std::string name;    
};

class Book: public Publisher {
public:
    Book(const std::string &name_ = "", const std::string &author_ = "");  
public:
    void publish() const override;        
    void use() const override;            
private:
    std::string author;          
};

class Film: public Publisher {
public:
    Film(const std::string &name_ = "", const std::string &director_ = "");   
public:
    void publish() const override;    
    void use() const override;        
private:
    std::string director;        

};
class Music:public Publisher{
public:
    Music(const std::string &name_ = "", const std::string &artist_ = "");
public:
    void publish() const override;        
    void use() const override;            
private:
    std::string artist;  
};

#include <iostream>
#include <string>
#include "publisher.hpp"
// Publisher类：实现
Publisher::Publisher(const std::string &name_): name {name_} {
}
// Book类: 实现
Book::Book(const std::string &name_ , const std::string &author_ ): Publisher{name_}, 
author{author_} {
}
void Book::publish() const {
std::cout << "Publishing book《" << name << "》 by " << author << '\n';
}
void Book::use() const {
std::cout << "Reading book 《" << name << "》 by " << author << '\n';
}
// Film类：实现
Film::Film(const std::string &name_, const std::string 
&director_):Publisher{name_},director{director_} {
}
void Film::publish() const {
std::cout << "Publishing film <" << name << "> directed by " << director << '\n';
}
void Film::use() const {
std::cout << "Watching film <" << name << "> directed by " << director << '\n';
}
// Music类：实现
Music::Music(const std::string &name_, const std::string &artist_): Publisher{name_}, 
artist{artist_} {
}
void Music::publish() const {
std::cout << "Publishing music <" << name << "> by " << artist << '\n';
}
void Music::use() const {
std::cout << "Listening to music <" << name << "> by " << artist << '\n';
}

#include <memory>
#include <iostream>
#include <vector>
#include "publisher.hpp"
void test1() {
std::vector<Publisher *> v;
v.push_back(new Book("Harry Potter", "J.K. Rowling"));
v.push_back(new Film("The Godfather", "Francis Ford Coppola"));
v.push_back(new Music("Blowing in the wind", "Bob Dylan"));
for(Publisher *ptr: v) {
ptr->publish();
ptr->use();
std::cout << '\n';
delete ptr;
    }
}
/*void test2() {
std::vector<std::unique_ptr<Publisher>> v;
v.push_back(std::make_unique<Book>("Harry Potter", "J.K. Rowling"));
v.push_back(std::make_unique<Film>("The Godfather", "Francis Ford Coppola"));
v.push_back(std::make_unique<Music>("Blowing in the wind", "Bob Dylan"));
for(const auto &ptr: v) {
ptr->publish();
ptr->use();
std::cout << '\n';
    }
}*/
void test3() {
Book book("A Philosophy of Software Design", "John Ousterhout");
book.publish();
book.use();
}
int main() {
std::cout << "运行时多态：纯虚函数、抽象类\n";
std::cout << "\n测试1: 使用原始指针\n";
test1();
//std::cout << "\n测试2: 使用智能指针\n";
//test2();
std::cout << "\n测试3: 直接使用类\n";
test3();
}

(2)运行结果

 （3）回答问题

1.1）有纯虚函数的类是抽象类。

virtual void publish() const = 0;

virtual void use() const = 0;

2）不能编译通过。因为Publisher类是抽象类，不能定义变量p。

2.1）

virtual void publish() const = 0;
virtual void use() const = 0;

2）报错信息是声明与定义不匹配。

3.1）声明类型为Publisher*。指向基类的指针。

2)Book类对象，Film类对象，Music类对象。

3）可能存在内存泄露，派生类清除不干净。

task2

（1）

#pragma once
#include <string>
// 图书描述信息类Book: 声明
class Book {
public:
    Book(const std::string &name_, 
         const std::string &author_, 
         const std::string &translator_, 
         const std::string &isbn_, 
         double price_);
    friend std::ostream& operator<<(std::ostream &out, const Book &book);
private:
    std::string name;        // 书名
    std::string author;      // 作者
    std::string translator;  // 译者
    std::string isbn;        // isbn号
    double price;        // 定价
};

#include <iomanip>
#include <iostream>
#include <string>
#include "book.hpp"
// 图书描述信息类Book: 实现
Book::Book(const std::string &name_, 
          const std::string &author_, 
          const std::string &translator_, 
          const std::string &isbn_, 
          double price_):name{name_}, author{author_}, translator{translator_}, 
isbn{isbn_}, price{price_} {
}
// 运算符<<重载实现
std::ostream& operator<<(std::ostream &out, const Book &book) {
    using std::left;
    using std::setw;
    
    out << left;
    out << setw(15) << "书名:" << book.name << '\n'
        << setw(15) << "作者:" << book.author << '\n'
        << setw(15) << "译者:" << book.translator << '\n'
        << setw(15) << "ISBN:" << book.isbn << '\n'
        << setw(15) << "定价:" << book.price;
    return out;
}

#pragma once
#include <string>
#include "book.hpp"
// 图书销售记录类BookSales：声明
class BookSale {
public:
    BookSale(const Book &rb_, double sales_price_, int sales_amount_);
    int get_amount() const;   // 返回销售数量
    double get_revenue() const;   // 返回营收
    
    friend std::ostream& operator<<(std::ostream &out, const BookSale &item);
private:
    Book rb;         
    double sales_price;      // 售价
    int sales_amount;       // 销售数量
};

#include <iomanip>
#include <iostream>
#include <string>
#include "booksale.hpp"
// 图书销售记录类BookSales：实现
BookSale::BookSale(const Book &rb_, 
double sales_price_, 
int sales_amount_): rb{rb_}, sales_price{sales_price_}, 
sales_amount{sales_amount_} {
}
int BookSale::get_amount() const {
return sales_amount;
}
double BookSale::get_revenue() const {
return sales_amount * sales_price;
}
// 运算符<<重载实现
std::ostream& operator<<(std::ostream &out, const BookSale &item) {
using std::left;
using std::setw;
out << left;
out << item.rb << '\n'
<< setw(15) << "售价:" << item.sales_price << '\n'
<< setw(15) << "销售数量:" << item.sales_amount << '\n'
<< setw(15) << "营收:" << item.get_revenue();
return out;
}

#include "booksale.hpp"
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
// 按图书销售数额比较
bool compare_by_amount(const BookSale &x1, const BookSale &x2) {
return x1.get_amount() > x2.get_amount();
}
void test() {
using namespace std;
 vector<BookSale> sales_lst;         // 存放图书销售记录
     int books_number;
    cout << "录入图书数量: ";
    cin >> books_number;
    cout << "录入图书销售记录" << endl;
    for(int i = 0; i < books_number; ++i) {
        string name, author, translator, isbn;
        float price;
        cout << string(20, '-') << "第" << i+1 << "本图书信息录入" << string(20, '-') << 
endl;
        cout << "录入书名: "; cin >> name;
        cout << "录入作者: "; cin >> author;
        cout << "录入译者: "; cin >> translator;
        cout << "录入isbn: "; cin >> isbn;
        cout << "录入定价: "; cin >> price;
        Book book(name, author, translator, isbn, price);
        float sales_price;
        int sales_amount;
        cout << "录入售价: "; cin >> sales_price;
        cout << "录入销售数量: "; cin >> sales_amount;
        BookSale record(book, sales_price, sales_amount);
        sales_lst.push_back(record);
    }
    // 按销售册数排序
    sort(sales_lst.begin(), sales_lst.end(), compare_by_amount);
    // 按销售册数降序输出图书销售信息
    cout << string(20, '=') <<  "图书销售统计" << string(20, '=') << endl;
    for(auto &t: sales_lst) {
        cout << t << endl;
        cout << string(40, '-') << endl;
    }
}
int main() {
    test();
}

（2）运行结果

 

 （3）回答问题

1.1）Book类中重载<<,Booksale类中重载<<

2）

std::ostream& operator<<(std::ostream &out, const BookSale &item) {
using std::left;
using std::setw;
out << left;
out << item.rb << '\n'
<< setw(15) << "售价:" << item.sales_price << '\n'
<< setw(15) << "销售数量:" << item.sales_amount << '\n'
<< setw(15) << "营收:" << item.get_revenue();
return out;
}

std::ostream& operator<<(std::ostream &out, const Book &book) {
using std::left;
using std::setw;

out << left;
out << setw(15) << "书名:" << book.name << '\n'
<< setw(15) << "作者:" << book.author << '\n'
<< setw(15) << "译者:" << book.translator << '\n'
<< setw(15) << "ISBN:" << book.isbn << '\n'
<< setw(15) << "定价:" << book.price;
return out;
}

2.1）

bool compare_by_amount(const BookSale &x1, const BookSale &x2) {
return x1.get_amount() <x2.get_amount();
}

task3

(1)

#include <iostream>
// 类A的定义
class A {
public:
A(int x0, int y0);
void display() const;
private:
int x, y;
};
A::A(int x0, int y0): x{x0}, y{y0} {
}
void A::display() const {
std::cout << x << ", " << y << '\n';
}
// 类B的定义
class B {
public:
B(double x0, double y0);
void display() const;
private:
double x, y;
};
B::B(double x0, double y0): x{x0}, y{y0} {
}
void B::display() const {
std::cout << x << ", " << y << '\n';
}
void test() {
std::cout << "测试类A: " << '\n';
A a(3, 4);
a.display();
std::cout << "\n测试类B: " << '\n';
B b(3.2, 5.6);
b.display();
}
int main() {
test();
}

运行结果

（2）

#include <iostream>
#include <string>
// 定义类模板
template<typename T>
class X{
public:
X(T x0, T y0);
void display();
private:
T x, y;
};
template<typename T>
X<T>::X(T x0, T y0): x{x0}, y{y0} {
}
template<typename T>
void X<T>::display() {
std::cout << x << ", " << y << '\n';
}
void test() {
std::cout << "测试1: 用int实例化类模板X" << '\n';
X<int> x1(3, 4);
x1.display();
std::cout << "\n测试2: 用double实例化类模板X" << '\n';
X<double> x2(3.2, 5.6);
x2.display();
std::cout << "\n测试3: 用string实例化类模板X" << '\n';
X<std::string> x3("hello", "oop");
x3.display();
}
int main() {
test();
}

运行结果

 task4

（1）

include<string>
#include<iostream>

class  MachinePet{
public:
    virtual ~MachinePet()=default;
    virtual std::string get_nickname()const=0;    
    virtual std::string talk() const=0;
};

class PetCat:public MachinePet{
public:
    PetCat(const std::string &nickname_):nickname(nickname_){}
public:
    std::string get_nickname()const override{return nickname;}
    std::string talk()const override{return"miao wu~";}
private:
    std::string nickname;
};
class PetDog:public MachinePet{
public:
    PetDog(const std::string &nickname_):nickname(nickname_){}
public:
    std::string get_nickname()const override{return nickname;}
    std::string talk()const override{return "wang wang~";}
private:
    std::string nickname;
};

#include <iostream>
#include <memory>
#include <vector>
#include "pets.hpp"
void test1() {
std::vector<MachinePet *> pets;
pets.push_back(new PetCat("miku"));
pets.push_back(new PetDog("da huang"));
for(MachinePet *ptr: pets) {
std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n';
delete ptr;  // 须手动释放资源
    }   
}
/*void test2() {
std::vector<std::unique_ptr<MachinePet>> pets;
pets.push_back(std::make_unique<PetCat>("miku"));
pets.push_back(std::make_unique<PetDog>("da huang"));
for(auto const &ptr: pets)
    std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n';
}*/
void test3() {
// MachinePet pet("little cutie");   // 编译报错：无法定义抽象类对象
const PetCat cat("miku");
std::cout << cat.get_nickname() << " says " << cat.talk() << '\n';
const PetDog dog("da huang");
std::cout << dog.get_nickname() << " says " << dog.talk() << '\n';
}
int main() {
std::cout << "测试1: 使用原始指针\n";
test1();
//std::cout << "\n测试2: 使用智能指针\n";
//test2();
std::cout << "\n测试3: 直接使用类\n";
test3();
}

（2）运行结果

task 5

 （1)

#pragma once
#include<iostream>

//template<typename T>
//class Complex;
//template<typename T>
//std::ostream& operator<<(std::ostream &out,const Complex<T> &c);
//template<typename T>
//std::istream& operator>>(std::istream &in,Complex<T> &c);
template<typename T>
class Complex{
public:
    Complex(T x0=0,T y0=0);
    T get_real()const{return x;}
    T get_imag()const{return y;}
    friend std::ostream& operator<<(std::ostream &out,const Complex<T> &c);
    friend std::istream& operator>>(std::istream &in,Complex<T> &c);
    Complex operator+(const Complex &c)const;
    Complex& operator+=(const Complex &c);
    bool operator==(const Complex &c)const;
private:
    T x,y;    
};

template<typename T>
Complex<T>::Complex(T x0,T y0):x(x0),y(y0){}

template<typename T>
Complex<T> Complex<T>::operator+(const Complex<T> &c)const
{
    return Complex<T>(x+c.x,y+c.y);
}

template<typename T>
Complex<T>& Complex<T>::operator+=(const Complex<T> &c)
{
    x+=c.x;
    y+=c.y;
    return *this; 
}

template<typename T>
std::ostream& operator<<(std::ostream &out,const Complex<T> &c){
    out<<c.x;
    if(c.y>=0) 
        out<<"+"<<c.y<<"i";
    else
        out<<c.y<<"i";
    return out;
}

template<typename T>
std::istream& operator>>(std::istream &in,Complex<T> &c){
    in>>c.x>>c.y;
    return in;
}

template<typename T>
bool Complex<T>::operator==(const Complex<T> &c)const
{
    return (x==c.x)&&(y==c.y);
}

#include <iostream>
#include "Complex.hpp"
void test1() {
using std::cout;
using std::boolalpha;
Complex<int> c1(2, -5), c2(c1);
cout << "c1 = " << c1 << '\n';
cout << "c2 = " << c2 << '\n';
cout << "c1 + c2 = " << c1 + c2 << '\n';
c1 += c2;
cout << "c1 = " << c1 << '\n';
cout << boolalpha << (c1 == c2) << '\n';
}
void test2() {
using std::cin;
using std::cout;
Complex<double> c1, c2;
cout << "Enter c1 and c2: ";
cin >> c1 >> c2;
cout << "c1 = " << c1 << '\n';
cout << "c2 = " << c2 << '\n';
const Complex<double> c3(c1);
cout << "c3.real = " << c3.get_real() << '\n';
cout << "c3.imag = " << c3.get_imag() << '\n';
}
int main() {
std::cout << "自定义类模板Complex测试1: \n";
test1();
std::cout << "\n自定义类模板Complex测试2: \n";
test2();
}

(2)运行结果