实验5 继承和多态

实验任务3

实验代码：

 1 #pragma once
 2 #include <iostream>
 3 #include <string>
 4 
 5 class MachinePets {
 6 public:
 7     MachinePets(const std::string& s);
 8     std::string get_nickname() const;
 9     virtual std::string talk()  = 0;
10 
11 protected:
12     std::string nickname;
13 };
14 
15 class PetCats : public MachinePets {
16 public:
17     PetCats(const std::string& s);
18     std::string talk()  ;
19 };
20 
21 class PetDogs : public MachinePets {
22 public:
23     PetDogs(const std::string& s);
24     std::string talk() ;
25 };
26 
27 
28 MachinePets::MachinePets(const std::string& s) : nickname(s) {}
29 
30 std::string MachinePets::get_nickname() const {
31     return nickname;
32 }
33 
34 
35 PetCats::PetCats(const std::string& s) : MachinePets(s) {}
36 
37 std::string PetCats::talk()  {
38     return "miao wu~";
39 }
40 
41 
42 PetDogs::PetDogs(const std::string& s) : MachinePets(s) {}
43 
44 std::string PetDogs::talk()  {
45     return "wang wang~";
46 }
pets.hpp

 

 1 #include <iostream>
 2 #include <vector>
 3 #include "pets.hpp"
 4 
 5 void test() {
 6     using namespace std;
 7 
 8     vector<MachinePets*> pets;
 9 
10     pets.push_back(new PetCats("miku"));
11     pets.push_back(new PetDogs("da huang"));
12 
13     for (auto& ptr : pets)
14         cout << ptr->get_nickname() << " says " << ptr->talk() << endl;
15 }
16 
17 int main() {
18     test();
19 }
task3.cpp

 

运行结果截图：

 

实验任务4：

实验代码：

 1 #pragma once
 2 #include <iostream>
 3 #include <string>
 4 #include <vector>
 5 #include <algorithm>
 6 
 7 class Film {
 8 public:
 9     friend std::istream& operator>>(std::istream& in, Film& f);
10     friend std::ostream& operator<<(std::ostream& out, const Film& f);
11     bool operator<(const Film& other) const;
12 
13 private:
14     std::string title;
15     std::string director;
16     std::string country;
17     int year;
18 };
19 
20 
21 
22 
23 std::istream& operator>>(std::istream& in, Film& f) {
24     std::cout << "录入片名: ";
25     in >> f.title;
26     std::cout << "录入导演: ";
27     in >> f.director;
28     std::cout << "录入制片国家/地区: ";
29     in >> f.country;
30     std::cout << "录入上映年份: ";
31     in >> f.year;
32     return in;
33 }
34 
35 std::ostream& operator<<(std::ostream& out, const Film& f) {
36     out << f.title << " " << f.director << " " << f.country << " " << f.year;
37     return out;
38 }
39 
40 bool Film::operator<(const Film& other) const {
41     return year < other.year;
42 }
43 
44 
45 bool compare_by_year(const Film& f1, const Film& f2) {
46     return f1< f2;
47 }
film.hpp
 1 #include "film.hpp"
 2 #include <iostream>
 3 #include <string>
 4 #include <vector>
 5 #include <algorithm>
 6 
 7 void test() {
 8     using namespace std;
 9     
10     int n;
11     cout << "输入电影数目: ";
12     cin >> n;
13 
14     cout << "录入" << n << "部影片信息" << endl;
15     vector<Film> film_lst;
16     for(int i = 0; i < n; ++i) {
17         Film f;
18         cout << string(20, '-') << "第" << i+1 << "部影片录入" << string(20, '-') << endl;
19         cin >> f;
20         film_lst.push_back(f);
21     }
22 
23     // 按发行年份升序排序
24     sort(film_lst.begin(), film_lst.end(), compare_by_year);
25 
26     cout << string(20, '=') + "电影信息(按发行年份)" +  string(20, '=')<< endl;
27     for(auto &f: film_lst)
28         cout << f << endl;
29 }
30 
31 int main() {
32     test();
33 }
task4.cpp

 

运行结果截图：

 实验任务5：

实验代码：

 1 #ifndef COMPLEX_HPP
 2 #define COMPLEX_HPP
 3 
 4 #include <iostream>
 5 #include <string>
 6 
 7 
 8 template <typename T>
 9 class Complex {
10 public:
11     
12     Complex(T real = 0, T imag = 0) : real(real), imag(imag) {}
13 
14     
15     Complex& operator+=(const Complex& other) {
16         real += other.real;
17         imag += other.imag;
18         return *this;
19     }
20 
21     Complex operator+(const Complex& other) const {
22         return Complex(real + other.real, imag + other.imag);
23     }
24 
25     bool operator==(const Complex& other) const {
26         return real == other.real && imag == other.imag;
27     }
28 
29     
30     friend std::istream& operator>>(std::istream& in, Complex& c) {
31         in >> c.real >> c.imag;
32         return in;
33     }
34 
35     friend std::ostream& operator<<(std::ostream& out, const Complex& c) {
36         out << c.real_<< (c.imag_ >= 0 ? "+" : "") << c.imag << "i";
37         return out;
38     }
39 
40     
41     T get_real() const { return real; }
42     T get_imag() const { return imag; }
43 
44 private:
45     T real;  
46     T imag;  
47 };
48 
49 #endif
Complex.hpp
 1 #include "Complex.hpp"
 2 #include <iostream>
 3 
 4 using std::cin;
 5 using std::cout;
 6 using std::endl;
 7 using std::boolalpha;
 8 
 9 void test1() {
10     Complex<int> c1(2, -5), c2(c1);
11 
12     cout << "c1 = " << c1 << endl;
13     cout << "c2 = " << c2 << endl;
14     cout << "c1 + c2 = " << c1 + c2 << endl;
15     
16     c1 += c2;
17     cout << "c1 = " << c1 << endl;
18     cout << boolalpha << (c1 == c2) << endl;
19 }
20 
21 void test2() {
22     Complex<double> c1, c2;
23     cout << "Enter c1 and c2: ";
24     cin >> c1 >> c2;
25     cout << "c1 = " << c1 << endl;
26     cout << "c2 = " << c2 << endl;
27 
28     cout << "c1.real = " << c1.get_real() << endl;
29     cout << "c1.imag = " << c1.get_imag() << endl;
30 }
31 
32 int main() {
33     cout << "自定义类模板Complex测试1: " << endl;
34     test1();
35 
36     cout << endl;
37 
38     cout << "自定义类模板Complex测试2: " << endl;
39     test2();
40 }
task5.cpp

 

运行结果截图：

 实验任务6：

实验代码：

 1 #pragma once
 2 class Date {
 3 private:
 4     int year;
 5     int month;
 6     int day;
 7     int totalDays;
 8 public:
 9     Date(int year, int month, int day);
10     int getYear()const { return year; }
11     int getMonth()const { return month; }
12     int getDay()const { return day; }
13     int getMaxDay()const;
14     bool isLeapYear()const {
15         return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
16     }
17     void show()const;
18     int operator-(const Date& date)const {
19         return totalDays - date.totalDays;
20     }
21 };
date.h
 1 #include<iostream>
 2 #include"date.h"
 3 #include<cstdlib>
 4 using namespace std;
 5 namespace {
 6     const int DAYS_BEFIRE_MONTH[] = { 0,31,59,90,120,151,181,212,243,273,304 ,334,365 };
 7 }
 8 Date::Date(int year, int month, int day) :year(year), month(month), day(day) {
 9     if (day <= 0 || day > getMaxDay()) {
10         cout << "Invalid date: ";
11         show();
12         cout << endl;
13         exit(1);
14     }
15     int years = year - 1;
16     totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFIRE_MONTH[month - 1] + day;
17     if (isLeapYear() && month > 2) totalDays++;
18 }
19 int Date::getMaxDay()const {
20     if (isLeapYear() && month == 2)
21         return 29;
22     else return DAYS_BEFIRE_MONTH[month] - DAYS_BEFIRE_MONTH[month - 1];
23 }
24 void Date::show()const {
25     cout << getYear() << "-" << getMonth() << "-" << getDay();
26 }
date.cpp
#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 amoount, 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.h
 1 #include "account.h"
 2 #include <cmath>
 3 #include<iostream>
 4 using namespace std;
 5 double Account::total = 0;
 6 Account::Account(const Date& date, const string& id) :id(id), balance(0) {
 7     date.show();
 8     cout << "\t#" << id << "created" << endl;
 9 }
10 void Account::record(const Date& date, double amount, const string& desc) {
11     amount = floor(amount * 100 + 0.5) / 100;
12     balance += amount;
13     total += amount;
14     date.show();
15     cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
16 }
17 void Account::show()const { cout << id << "\tBalance:" << balance; }
18 void Account::error(const string& msg)const {
19     cout << "Error(#" << id << "):" << msg << endl;
20 }
21 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate) :Account(date, id), rate(rate), acc(date, 0) {}
22 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
23     record(date, amount, desc);
24     acc.change(date, getBalance());
25 }
26 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
27     if (amount > getBalance()) {
28         error("not enough money");
29     }
30     else {
31         record(date, -amount, desc);
32         acc.change(date, getBalance());
33     }
34 }
35 void SavingsAccount::settle(const Date& date) {
36     double interest = acc.getSum(date) * rate / (date - Date(date.getYear() - 1, 1, 1));
37     if (interest != 0)record(date, interest, "interest");
38     acc.reset(date, getBalance());
39 }
40 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) {}
41 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
42     record(date, amount, desc);
43     acc.change(date, getDebt());
44 }
45 void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
46     if (amount - getBalance() > credit) {
47         error("not enouogh credit");
48     }
49     else {
50         record(date, -amount, desc);
51         acc.change(date, getDebt());
52     }
53 }
54 void CreditAccount::settle(const Date& date) {
55     double interest = acc.getSum(date) * rate;
56     if (interest != 0) record(date, interest, "interest");
57     if (date.getMonth() == 1)record(date, -fee, "annual fee");
58     acc.reset(date, getDebt());
59 }
60 void CreditAccount::show()const {
61     Account::show();
62     cout << "\tAvailable credit:" << getAvailableCredit();
63 }
account.cpp
 1 #pragma once
 2 #include"date.h"
 3 class Accumulator {
 4 private:
 5     Date lastDate;
 6     double value;
 7     double sum;
 8 public:
 9     Accumulator(const Date& date, double value) :lastDate(date), value(value), sum{ 0 } {}
10     double getSum(const Date& date) const {
11         return sum + value * (date - lastDate);
12     }
13     void change(const Date& date, double value) {
14         sum = getSum(date);
15         lastDate = date;
16         this->value = value;
17     }
18     void reset(const Date& date, double value) {
19         lastDate = date;
20         this->value;
21         sum = 0;
22     }
23 };
accumulator.h
 1 #include"account.h"
 2 #include<iostream>
 3 using namespace std;
 4 
 5 int main() {
 6     Date date(2008, 11, 1);
 7     SavingsAccount sa1(date, "S3755217", 0.015);
 8     SavingsAccount sa2(date, "02342342", 0.015);
 9     CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);
10     Account* accounts[] = { &sa1,&sa2,&ca };
11     const int n = sizeof(accounts) / sizeof(Account*);
12     cout << "(d)deposit (w)withdraw (s)show (c)change day (n)next month (e)exit" << endl;
13     char cmd;
14     do {
15         date.show();
16         cout << "\tTotal:" << Account::getTotal() << "\tcommand>";
17         int index, day;
18         double amount;
19         string desc;
20         cin >> cmd;
21         switch (cmd) {
22         case 'd':
23             cin >> index >> amount;
24             getline(cin, desc);
25             accounts[index]->deposit(date, amount, desc);
26             break;
27 
28         case 'w':
29             cin >> index >> amount;
30             getline(cin, desc);
31             accounts[index]->withdraw(date, amount, desc);
32             break;
33 
34         case 's':
35             for (int i = 0; i < n; i++) {
36                 cout << "[" << i << "]";
37                 accounts[i]->show();
38                 cout << endl;
39             }
40             break;
41 
42         case 'c':
43             cin >> day;
44             if (day < date.getDay()) {
45                 cout << "You cannot specify a previous day";
46             }
47             else if (day > date.getMaxDay())
48                 cout << "Invalid day";
49             else date = Date(date.getYear(), date.getMonth(), day);
50             break;
51 
52         case 'n':
53             if (date.getMonth() == 12)
54                 date = Date(date.getYear() + 1, 1, 1);
55             else date = Date(date.getYear(), date.getMonth() + 1, 1);
56             for (int i = 0; i < n; i++) {
57                 accounts[i]->settle(date);
58             }
59             break;
60         }
61     } while (cmd != 'e');
62     return 0;
63 }
8_8.cpp

 

实验结果截图：

好处：Account 中将账户的公共操作都声明为虚函数，因此可以通过基类的指针来执行各种操作，因而各种类型的账户对象都可以通过一个基类指针数组来访问，使得我们可以通过一个统一的方式来操作各个账户。

不足：账户是在程序一开始创建好的，不能通过用户自己输入来创建，程序比较局限。

posted @ 2024-12-02 21:54  宿雨如秋  阅读(4)  评论(0)  编辑  收藏  举报