实验伍

实验5 继承和多态

实验任务3

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->get_nickname() << " says " << ptr->talk() << endl;
}
int main() {
    test();
}

pets.hpp

#pragma once
#include<iostream>
using namespace std;

class MachinePets
{
    private:
    string nickname;
    public:
    MachinePets(const string &s);//const
    virtual string talk()const=0;//virtual
    string get_nickname()const;//
};

MachinePets::MachinePets(const string & s):nickname{s}{}

string MachinePets::get_nickname()const{
    return nickname;
}

class PetCats:public MachinePets{
    public:
    PetCats(const string & s);
    string talk()const override;//override
};

PetCats::PetCats(const string & s):MachinePets{s}{}

string PetCats::talk()const{
    return "miao wu~";
}

class PetDogs:public MachinePets{
    public:
    PetDogs(const string & s);
    string talk()const override;
};

PetDogs::PetDogs(const string &s):MachinePets{s}{}
string PetDogs::talk()const{
    return "wang wang~";
}

试验任务4

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();
}

fill.hpp

#pragma once
#include <iostream>
#include <iomanip> //setw
using namespace std;

class Film
{
private:
    string name, director, area, time;

public:
   Film(const string &name="", const string &director="", const string &area="", const string &time="");

    friend ostream &operator<<(ostream &out, const Film &f); //

    friend istream &operator>>(istream &in,Film &f);
    string get_year() const; //
};

Film::Film(const string &name, const string &director, const string &area, const string &time)
{
    this->name = name;
    this->director = director;
    this->area = area;
    this->time;
}

string Film::get_year() const
{
    return time;
}

ostream &operator<<(ostream &out, const Film &f)
{
    out << f.name << setw(12) << f.director << setw(12) << f.area << setw(12) << f.time << "\n";
    return out;
}

istream &operator>>(istream& in,Film& f)
{
    cout<<"录入片名：";
    in>>f.name;
    cout<<"录入导演：";
    in>>f.director;
    cout<<"录入制片地区：";
    in>>f.area;
    cout<<"录入上映年份：";
    in>>f.time;
    // in>>f.name>>f.director>>f.area>>f.time;
    return in;
}

bool compare_by_year(const Film& f1,const Film& f2)
{
    return f1.get_year()<f2.get_year();
}

实验任务5：

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();
}

Complex.hpp

#pragma once
#include<iostream>
using namespace std;

template<typename T>
class Complex{
    public:
    Complex(const T& r=0,const T& l=0):
    real{r},imag{l}{}
    Complex operator +=(const Complex &c)
    {
        real+=c.real;
        imag+=c.imag;
        return *this;
    }

    friend Complex operator+(const Complex &c1,const Complex &c2)
    {
        return Complex<T>(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 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;
    }

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

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

    private:
    T real;
    T imag;
};

实验任务6：

date.cpp

#include"date.h"
#include<iostream>
#include<cstdlib>
using namespace std;
namespace {
	const int DAYS_BEFIRE_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_BEFIRE_MONTH[month - 1] + day;
	if (isLeapYear() && month > 2) totalDays++;
}
int Date::getMaxDay()const {
	if (isLeapYear() && month == 2)
		return 29;
	else return DAYS_BEFIRE_MONTH[month] - DAYS_BEFIRE_MONTH[month - 1];
}
void Date::show()const {
	cout << getYear() << "-" << getMonth() << "-" << getDay();
}

accumulator.h

#pragma once
#include "date.h"
class Accumulator {
private:
	Date lastDate;
	double value;
	double sum;
public:
	Accumulator(const Date& date, double value) :lastDate(date), value(value), sum{ 0 } {}
	double getSum(const Date& date) const {
		return sum + value * (date-lastDate);
	}
	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;
	}
};

account.h

#pragma once
#include"date.h"
#include"accumulator.h"
#include<string>
using namespace std;
class Account {
private:
	string id;
	double balance;
	static double total;
protected:
	Account(const Date& date, const string& id);
	void record(const Date& date, double amount, const string& desc);
	void error(const string& msg) const;
public:const string& getId() { return id; }
	  double getBalance()const { return balance; }
	  static double getTotal() { return total; }
	  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;
};
class SavingsAccount :public Account {
private:
	Accumulator acc;
	double rate;
public:
	SavingsAccount(const Date& date, const string& id, double rate);
	double getRate() const { return  rate; }
	void deposit(const Date& date, double amount, const string& desc);
	void withdraw(const Date& date, double amount, const string& desc);
	void settle(const Date& date);
};
class CreditAccount :public Account {
private:
	Accumulator acc;
	double credit;
	double rate;
	double fee;
	double getDebt()const {
		double balance = getBalance();
		return(balance < 0 ? balance : 0);
	}
public:CreditAccount(const Date& date, const 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 string& desc);
	  void withdraw(const Date& date, double amount, const string& desc);
	  void settle(const Date& date);
	  void show()const;
};

account.cpp

#include "account.h"
#include <cmath>
#include<iostream>
using namespace std;
double Account::total = 0;
Account::Account(const Date& date, const string& id) :id(id), balance(0) {
	date.show();
	cout << "\t#" << id << "created" << endl;
}
void Account::record(const Date& date, double amount, const 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 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 enouogh 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();
}

main.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 << "Invalid 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;
}

date.h

#pragma once
class Date {
private:
	int year;
	int month;
	int day;
	int totalDays;
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;
	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;
	}
};

改进的地方：在基类账户中将公共操作都声明为虚函数，这样可以通过基类指针来执行各种操作，很方便。

有待改善的地方：最好不要允许用户随时动态添加新的账户。