实验5

实验任务1

源代码：

publisher.cpp:

#include <iostream>
#include <string>
#include "publisher.hpp"

Publisher::Publisher(const std::string &name_): name {name_} {
}

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::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::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';
}

publish.hpp:

#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;
};

task1.cpp:

#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();
}

运行结果截图：

问题1：

（1）Publisher类里有纯虚函数virtual void publish() const = 0;和virtual void use() const = 0;

（2）编译不通过，抽象类只能作为基类被继承，不能被创建

问题2：

（1）void publish() const override; void use() const override;

（2）

问题3：

（1）Publisher类的指针

（2）Book,Film,Music

（3）析构函数声明为virtual作用是删除基类指针时会调用子类的析构函数，保证内存释放，若删除virtual，执行delete ptr;会导致子类中的部分成员无法释放内存

 

实验任务2：

源代码：

book.hpp:

#pragma once
#include <string>

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;
    std::string author;
    std::string translator;
    std::string isbn;
    double price;
};

book.cpp:

#include <iomanip>
#include <iostream>
#include <string>
#include "book.hpp"


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_} {
}

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;
} 

booksale.hpp:

#pragma once

#include <string>
#include "book.hpp"

class BookSale {
public:
    BookSale(const Book &rb_, double sales_price_, int sales_amount_);
    int get_amount() const;
    double get_revenue() const;
    
    friend std::ostream& operator<<(std::ostream &out, const BookSale &item);

private:
    Book rb;         
    double sales_price;
    int sales_amount;
};

booksale.cpp:

#include <iomanip>
#include <iostream>
#include <string>
#include "booksale.hpp"

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;
}

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;
}

task2.cpp:

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <string>
#include <vector>
#include "booksale.hpp"

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

void test() {
    using std::cin;
    using std::cout;
    using std::getline;
    using std::sort;
    using std::string;
    using std::vector;
    using std::ws;

    vector<BookSale> sales_records;

    int books_number;
    cout << "录入图书数量: ";
    cin >> books_number;

    cout << "录入图书销售记录\n";
    for(int i = 0; i < books_number; ++i) {
        string name, author, translator, isbn;
        double price;
        cout << string(20, '-') << "第" << i+1 << "本图书信息录入" << string(20, '-') << '\n';
        cout << "录入书名: "; getline(cin>>ws, name);
        cout << "录入作者: "; getline(cin>>ws, author);
        cout << "录入译者: "; getline(cin>>ws, translator);
        cout << "录入isbn: "; getline(cin>>ws, isbn);
        cout << "录入定价: "; cin >> price;

        Book book(name, author, translator, isbn, price);

        double 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_records.push_back(record);
    }

    sort(sales_records.begin(), sales_records.end(), compare_by_amount);

    cout << string(20, '=') <<  "图书销售统计" << string(20, '=') << '\n';
    for(auto &record: sales_records) {
        cout << record << '\n';
        cout << string(40, '-') << '\n';
    }
}

int main() {
    test();
}

运行结果截图：

问题1：

（1）<<被重载了2处，第一处用于Book类型，第二处用于BookSale类型

（2）cout << record << '\n';和out << item.rb << '\n'

问题2：

（1）使用sort排序，按照bool compare_by_amount(const BookSale &x1, const BookSale &x2) {return x1.get_amount() > x2.get_amount();}

（2）sort(sales_1st.begin(),sales_1st.end(),[](const BookSale &x1,const BookSale &x2){return x1.get_amount()>x2.get_amount()});

 

实验任务4：

源代码：

pet.hpp:

#pragma once
#include<string>

class MachinePet{
public:
    MachinePet(const std::string& name):nickname(name){}
    virtual std::string talk() const=0;
    std::string get_nickname() const{
        return nickname;
    }
    virtual ~MachinePet()=default;
    
protected:
    std::string nickname;
};

class PetCat:public MachinePet{
public:
    PetCat(const std::string& name):MachinePet(name){}
    std::string talk() const override{
    return "miao wu~";
    }
};

class PetDog:public MachinePet{
public:
    PetDog(const std::string& name):MachinePet(name){}
    std::string talk() const override{
    return "wang wang~";
    }
};

task4.cpp:

#include <iostream>
#include <memory>
#include <vector>
#include "pet.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() {
    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();
}

运行结果截图：

 

 

实验任务5：

源代码：Complex.hpp:

#pragma once
#include<iostream>

template<typename T>
class Complex{
public:
    Complex():real(T()),imag(T()){}
    Complex(T r,T i):real(r),imag(i){}
    Complex(const Complex& other):real(other.real),imag(other.imag){}
    
    T get_real() const{
        return real;
    }
    T get_imag() const{
        return imag;
    }
    
    friend Complex& operator+=(Complex& x,Complex& y){
        x.real+=y.real;
        x.imag+=y.imag;
        return x;
    }
    
    friend Complex& operator+(Complex& x,Complex& y){
        x+=y;
        return x;
    }
    
    friend bool operator==(Complex& x,Complex& y){
        return (x.real==y.real)&&(x.imag==y.imag);
    }
    
    friend std::istream& operator>>(std::istream& in,Complex& x){
        in>>x.real>>x.imag;
    }
    
    friend std::ostream& operator<<(std::ostream& out,Complex& x){
        out<<x.real;
        if(x.imag>=0){
            out<<"+"<<x.imag<<"i";
        }
        else{
            out<<-x.imag<<"i";
        }
        return out;
    }
    
private:
    T real;
    T imag;
};

task5.cpp:

#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();
}

运行结果截图：