实验五 继承和多态

实验任务1

publisher.hpp

#pragma once

#include <iostream>
#include <string>

using std::cout;
using std::endl;
using std::string;

// 发行/出版物类：Publisher （抽象类）
class Publisher {
public:
    Publisher(const string &s = "");            // 构造函数

public:
    virtual void publish() const = 0;                 // 纯虚函数，作为接口继承
    virtual void use() const = 0;                     // 纯虚函数，作为接口继承

protected:
    string name;    // 发行/出版物名称
};

Publisher::Publisher(const string &s): name {s} {
}


// 图书类: Book
class Book: public Publisher {
public:
    Book(const string &s = "", const string &a = "");  // 构造函数

public:
    void publish() const override;        // 接口
    void use() const override;            // 接口

private:
    string author;          // 作者
};

Book::Book(const string &s, const string &a): Publisher{s}, author{a} {
}

void Book::publish() const {
    cout << "Publishing book: 《" << name << "》 by " << author << endl;
}

void Book::use() const {
    cout << "Reading book: " << name << " by " << author << endl;
}


// 电影类: Film
class Film: public Publisher {
public:
    Film(const string &s = "", const string &d = "");   // 构造函数

public:
    void publish() const override;    // 接口
    void use() const override;        // 接口            

private:
    string director;        // 导演
};

Film::Film(const string &s, const string &d): Publisher{s}, director{d} {
}

void Film::publish() const {
    cout << "Publishing film: <" << name << "> directed by " << director << endl;
}

void Film::use() const {
    cout << "Watching film: " << name << " directed by " << director << endl;
}


// 音乐类：Music
class Music: public Publisher {
public:
    Music(const string &s = "", const string &a = "");

public:
    void publish() const override;        // 接口
    void use() const override;            // 接口

private:
    string artist;      // 音乐艺术家名称
};

Music::Music(const string &s, const string &a): Publisher{s}, artist{a} {
}

void Music::publish() const {
    cout << "Publishing music <" << name << "> by " << artist << endl;
}

void Music::use() const {
    cout << "Listening to music: " << name << " by " << artist << endl;
}

task1.cpp

#include "publisher.hpp"
#include <vector>
#include <typeinfo>

using std::vector;

void test() {
   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(auto &ptr: v) {
        cout << "pointer type: " << typeid(ptr).name() << endl;  // 输出指针类型
        cout << "RTTI type: " << typeid(*ptr).name() << endl;    // 输出指针指向的对象类型
        ptr->publish();
        ptr->use();
        cout << endl;
   }
}

int main() {
    test();
}

运行结果截图

实验任务2

book.hpp

#pragma once

#include <string>
#include <iostream>
#include <iomanip>

using std::string;
using std::ostream;
using std::endl;
using std::setw;
using std::left;

class Book {
public:
    Book(const string& name, const string& author, const string& translator, const string& isbn, float price);

    friend ostream& operator<<(ostream& out, const Book& book);

private:
    string name;        // 书名
    string author;      // 作者
    string translator;  // 译者
    string isbn;        // isbn号
    float price;        // 定价
};

// 成员函数实现
Book::Book(const string& name, const string& author, const string& translator, const string& isbn, float price) {
    this->name = name;
    this->author = author;
    this->translator = translator;
    this->isbn = isbn;
    this->price = price;
}

// 友元实现
ostream& operator<<(ostream& out, const Book& book) {
    out << left;
    out << setw(15) << "书名:" << book.name << endl
        << setw(15) << "作者:" << book.author << endl
        << setw(15) << "译者:" << book.translator << endl
        << setw(15) << "ISBN:" << book.isbn << endl
        << setw(15) << "定价:" << book.price;

    return out;
}

booksale.hpp

#pragma once

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

using std::string;
using std::cout;
using std::endl;
using std::setw;

class BookSale {
public:
    BookSale(const Book& b, float price, int amount);
    int get_amount() const;

    friend ostream& operator<<(ostream& out, const BookSale& item);

private:
    Book rb;
    float sales_price;      // 售价
    int sales_amount;       // 销售数量
    float revenue;          // 营收
};

// 成员函数实现
BookSale::BookSale(const Book& b, float price, int amount) : rb{ b }, sales_price(price), sales_amount{ amount } {
    revenue = sales_amount * sales_price;
}

int BookSale::get_amount() const {
    return sales_amount;
}

// 友元函数实现
ostream& operator<<(ostream& out, const BookSale& item) {
    out << left;
    out << item.rb << endl
        << setw(15) << "售价:" << item.sales_price << endl
        << setw(15) << "销售数量:" << item.sales_amount << endl
        << setw(15) << "营收:" << item.revenue;

    return out;
}

task2.cpp

#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();
}

运行结果截图

1.把operator<<定义为booksale类的友元函数，把booksale类的对象输出为ostream对象

2.调用标准库的函数sort，具体代码实现为sort(sales_lst.begin(), sales_lst.end(), compare_by_amount);

3.在booksale的构造函数中对book初始化，BookSale(const Book& b, float price, int amount);

实验任务3

pets.hpp

#include<iostream>
#include<string>

using std::endl;
using std::cout;
using std::string;
using std::ostream;
class MachinePets {
public:
    MachinePets(const string &s);
    string get_nickname()const;
    friend ostream& operator<<(ostream& out, const MachinePets&);
public:
    virtual void  talk() const = 0;
protected:
    string nickname;
};
MachinePets::MachinePets(const string &s):nickname(s){}
string MachinePets::get_nickname() const {
    return nickname;
}
ostream& operator<<(ostream& out, const MachinePets& m) {
    out << m.get_nickname()<<" says ";
    m.talk();
    return out;
}
class PetCats:public MachinePets {
public:
    PetCats(const string& a);
public:
    virtual void talk() const override;
private:
    string catname;
};
PetCats::PetCats(const string& a) :MachinePets(a),catname(a){}
void PetCats::talk() const { cout<<"miao wu~"; }
class PetDogs :public MachinePets {
public:
    PetDogs(const string& d);
public:
    virtual void  talk() const override;
private:
    string dogname;
};
PetDogs::PetDogs(const string& d) :MachinePets(d),dogname(d){}
void PetDogs::talk() const { cout <<"wang wang~"; }

task3.cpp

#include <iostream>
#include <vector>
#include "pets.hpp"

void test() {
    using namespace std;

    vector<MachinePets*> pets;

    pets.push_back(new PetCats("miku"));
    pets.push_back(new PetDogs("da huang"));

    for (auto& ptr : pets)
        cout <<*ptr << endl;
}

int main() {
    test();
}

运行结果截图

 实验任务4

film.hpp

#include<iostream>
#include<string>
#include<iomanip>

using std::cout;
using std::endl;
using std::cin;
using std::string;
using std::istream;
using std::ostream;
using std::left;
using std::setw;
class Film {
public:
    Film();
    friend istream& operator>>(istream& in,  Film& );
    friend ostream& operator<<(ostream& out, Film&);
    friend bool compare_by_year(const Film& f1, const Film& f2);
private:
    string name;
    string director;
    string area;
    string year;
};
Film::Film() : name(""), director(""), area(""), year("") {}
istream& operator>>(istream& in, Film& f) {
        cout << "录入片名：";
        in >> f.name;
        cout << "录入导演：";
        in >> f.director;
        cout << "录入制片国家/地区：";
        in >> f.area;
        cout << "录入上映年份：";
        in >> f.year;
    return in;
}
ostream& operator<<(ostream& out, Film& f) {
    out << left;
    out <<setw(15)<<f.name;
    out << setw(15) << f.director;
    out << setw(15) << f.area;
    out << setw(15) << f.year;
    return out;
}
bool compare_by_year(const Film& f1, const Film& f2) {
    return (f1.year < f2.year);
}

task4.cpp

#include "film.hpp"
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
void test() {
    using namespace std;

    int n;
    cout << "输入电影数目: ";
    cin >> n;

    cout << "录入" << n << "部影片信息" << endl;
    vector<Film> film_lst;
    for (int i = 0; i < n; ++i) {
        Film f;
        cout << string(20, '-') << "第" << i + 1 << "部影片录入" << string(20, '-') << endl;
        cin >> f;
        film_lst.push_back(f);
    }

    // 按发行年份升序排序
    sort(film_lst.begin(), film_lst.end(), compare_by_year);

    cout << string(20, '=') + "电影信息(按发行年份)" + string(20, '=') << endl;
    for (auto& f : film_lst)
        cout << f  << endl;
}

int main() {
    test();
}

运行结果截图

实验任务5

Complex.hpp

#include <iostream>

using std::cout;
using std::endl;
using std::istream;
using std::ostream;

template<typename T>
class Complex {
public:
    Complex(T r = 0, T i = 0) : real(r), imag(i) {}

    Complex& operator+=(const Complex& c) {
        real += c.real;
        imag += c.imag;
        return *this;
    }

    T get_real() const { return real; }
    T get_imag() const { return imag; }

    Complex(const Complex& c) : real(c.real), imag(c.imag) {}

    friend Complex operator+(const Complex& c1, const Complex& c2) {
        return Complex(c1.real + c2.real, c1.imag + c2.imag);
    }

    friend bool operator==(const Complex& c1, const Complex& c2) {
        return (c1.real == c2.real && c1.imag == c2.imag);
    }

    friend istream& operator>>(istream& in, Complex& c) {
        in >> c.real >> c.imag;
        return in;
    }

    friend ostream& operator<<(ostream& out, const Complex& c) {
        if (c.imag >= 0)
            out << c.real << "+" << c.imag << "i";
        else
            out << c.real << c.imag << "i";
        return out;
    }

private:
    T real, imag;
};

task5.cpp

#include "Complex.hpp"
#include <iostream>

using std::cin;
using std::cout;
using std::endl;
using std::boolalpha;

void test1() {
    Complex<int> c1(2, -5), c2(c1);

    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c1 + c2 = " << c1 + c2 << endl;

    c1 += c2;
    cout << "c1 = " << c1 << endl;
    cout << boolalpha << (c1 == c2) << endl;
}

void test2() {
    Complex<double> c1, c2;
    cout << "Enter c1 and c2: ";
    cin >> c1 >> c2;
    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;

    cout << "c1.real = " << c1.get_real() << endl;
    cout << "c1.imag = " << c1.get_imag() << endl;
}

int main() {
    cout << "自定义类模板Complex测试1: " << endl;
    test1();

    cout << endl;

    cout << "自定义类模板Complex测试2: " << endl;
    test2();
}

运行结果截图

实验任务6

 date.h

#ifndef _DATE_H
#define _DATE_H
#include<iostream>
#include<string>
using namespace std;
class Date
{
private:
    int year;
    int month;
    int day;
    int totalDays;//该日期是从公元元年1月1日开始的第几天
public:
    Date(int year, int month, int day);
    int getYear() const { return year; }
    int getMonth() const { return month; }
    int getDay() const { return day; }
    int getMaxDay() const;//获得当月有多少天
    bool isLeapYear() const  {
        return (year % 4 == 0 && year %100 != 0 || year % 400 == 0);
    }
    void show()const;
    int  operator-(const Date& date)const {
        return totalDays-date.totalDays ;
    }
};
#endif

date.cpp

#include "date.h"
#include<iostream>
#include<cstdlib>
using namespace std;
namespace {
    const int DAYS_BEFORE_MONTH[] = { 0,31,59,90,120,151,181,212,243,273,304,334,365 };

}
Date::Date(int year, int month, int day) :year(year), month(month), day(day) {
    if (day <= 0 || day > getMaxDay()) {
        cout << "Invalid date:";
        show();
        cout << endl;
        exit(1);
    }
    int years = year - 1;
    totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day;
    if (isLeapYear() && month > 2) totalDays++;
}
int Date::getMaxDay() const {
    if (isLeapYear() && month == 2)
        return 29;
    else
        return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
}
void Date::show()const {
    cout << getYear() << "-" << getMonth() << "-" << getDay();
}

accumulator.h

#ifndef _ACCUMULATOR_H_
#define _ACCUMULATOR_H_
#include"date.h"
class Accumulator
{
private:
    Date lastDate;//上次变更数值的日期
    double value;//当前数值
    double sum;//数值按日累加之和
public:
    double getSum(const Date&date)const { 
        return     sum + value*(date - lastDate);
    }
    Accumulator(const Date& date, double value) :
        lastDate(date), value(value), sum(0) {}
    void change(const Date& date, double value) {
        sum = getSum(date);
        lastDate = date;
        this->value = value;
    }
    void reset(const Date& date, double value) {
        lastDate = date;
        this->value = value;
        sum = 0;
    }
};
#endif

account.h

#ifndef _ACCOUNT_H_
#define _ACCOUNT_H_
#include"date.h"
#include"accumulator.h"
#include<string>
using std::string;
class Account
{
private:
    string id;
    double balance;//余额
    static double total;//账户总金额
protected:
    Account(const Date& date, const string &id);
    void record(const Date& date, double amount, const string &desc);//记录一笔账
    void error(const std::string& msg)const;
public:
    const string &getId() const { return id; }
    double getBalance() const { return balance; }
    virtual void deposit(const Date& date, double amount, const string& desc) =0;
    virtual void withdraw(const Date& date, double amount, const string& desc) =0;
    virtual void settle(const Date& date)=0;
    virtual void show()const;
    static double getTotal(){ return total; }
};
class SavingsAccount :public Account {          //存储账户类
private:
    Accumulator acc;
    double rate;
public:
    SavingsAccount(const Date& date, const std::string& id, double rate);
    double getRate() const { return rate; }
    void deposit(const Date& date, double amount, const std::string& desc);
    void withdraw(const Date& date, double amount, const std::string& desc);
    void settle(const Date& date);//结算利息，每年一月一日调用一次该函数
};
class CreditAccount :public Account {   //信用账户类
private:
    Accumulator acc;
    double credit;
    double rate;
    double fee;
    double getDebt() const {        //获得欠款额
        double balance = getBalance();
        return (balance < 0 ? balance : 0);
    }
public:
    CreditAccount(const Date& date, const std::string& id, double credit, double rate, double fee);
    double getCredit() const { return credit; }
    double getRate() const { return rate; }
    double getFee() const { return fee; }
    double getAvailableCredit() const {
        if (getBalance() < 0) {
            return credit + getBalance();
        }
        else
            return credit;
    }
    void deposit(const Date& date, double amount, const std::string& desc);
    void withdraw(const Date& date, double amount, const std::string& desc);
    void settle(const Date& date);
    void show() const;
};
#endif

account.cpp

#include "account.h"
#include<cmath>
#include<iostream>
#include<string>
using namespace std;
double Account::total = 0;

Account::Account(const Date& date, const std::string& id) :id(id), balance(0) {
    date.show();
    cout << "\t#" << id << " created" << endl;
}
void Account::record(const Date& date, double amount, const std::string& desc) {
    amount = floor(amount * 100 + 0.5) / 100;
    balance += amount;
    total += amount;
    date.show();
    cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
}
void Account::show()const {
    cout << id << "\tBalance" << balance;
}
void Account::error(const string& msg) const {
    cout << "Error(#" << id << "):" << msg << endl;
}
SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate)
    :Account(date, id), rate(rate), acc(date, 0) {}
void SavingsAccount::deposit(const Date& date, double amount, const std::string& desc) {
    record(date, amount, desc);
    acc.change(date, getBalance());
}
void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
    if (amount > getBalance()) {
        error("not enough money");
    }
    else {
        record(date, -amount, desc);
        acc.change(date, getBalance());
    }
}
void SavingsAccount::settle(const Date& date) {
    if (date.getMonth() == 1) {
        double interest = acc.getSum(date) * rate
            / (date - Date(date.getYear() - 1, 1, 1));
        if (interest != 0)
            record(date, interest, "interest");
        acc.reset(date, getBalance());
    }
}
CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee) :Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) {}
void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
    record(date, amount, desc);
    acc.change(date, getDebt());
}
void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
    if (amount - getBalance() > credit) {
        error("not enough credit");
    }
    else {
        record(date, -amount, desc);
        acc.change(date, getDebt());
    }
}
void CreditAccount::settle(const Date& date) {
    double interest = acc.getSum(date) * rate;
    if (interest != 0) record(date, interest, "interest");
    if (date.getMonth() == 1)
        record(date, -fee, "annual fee");
    acc.reset(date, getDebt());
}
void CreditAccount::show() const {
    Account::show();
    cout << " \tAvailable credit:" << getAvailableCredit();
}

8_8.cpp

#include"account.h"
#include<iostream>
using namespace std;
int main() {
    Date date(2008, 11, 1);
    SavingsAccount sa1(date, "S3755217", 0.015);
    SavingsAccount sa2(date, "02342342", 0.015);
    CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);
    Account* accounts[] = { &sa1,&sa2,&ca };
    const int n = sizeof(accounts) / sizeof(Account*); 
    cout << "(d)deposit (w)withdraw (s)show (c)change day (n)next month (e)exit" << endl;
    char cmd;
    do {
        date.show();
        cout << "\tTotal:" << Account::getTotal() << "\tcommand>";
        int index, day;
        double amount;
        string desc;
        cin >> cmd;
        switch (cmd) {
        case 'd':
            cin >> index >> amount;
            getline(cin, desc);
            accounts[index]->deposit(date, amount, desc);
            break;
        case 'w':
            cin >> index >> amount;
            getline(cin, desc);
            accounts[index]->withdraw(date, amount, desc);
            break;
        case 's':
            for (int i = 0;i < n;i++) {
                cout << "[" << i << "]";
                accounts[i]->show();
                cout << endl;
            }
                break;
        case 'c':
            cin >> day;
            if (day < date.getDay())
                cout << "You cannot specify a previous day";
            else if (day > date.getMaxDay())
                cout << "Inalid day";
            else
                date = Date(date.getYear(), date.getMonth(), day);
            break;
        case 'n':
            if (date.getMonth() == 12)
                date = Date(date.getYear() + 1, 1, 1);
            else
                date = Date(date.getYear(), date.getMonth() + 1, 1);
            for (int i = 0;i < n;i++)
                accounts[i]->settle(date);
            break;

            }
        }while (cmd != 'e');
        return 0;
    }

运行结果截图

总结：

运用了operator-运算符的重载，并创建了抽象类Account，并将Account基类中的公共操作都声明为虚函数，因此可以通过基类指针来执行各种操作