实验5 继承和多态

实验任务3：

pets.hpp代码：

 1  #pragma once
 2  #include <iostream>
 3  #include <string>
 4  using std::string;
 5  
 6  class MachinePets {
 7  public:
 8      // 带参数的构造函数
 9      MachinePets(const string& s) : nickname(s) {} 
10      // 纯虚函数，宠物叫声的统一接口
11      virtual string talk() const = 0;
12      // 获取机器宠物的昵称
13      string get_nickname() const { return nickname; }
14  
15  protected:
16      string nickname; // 昵称
17  };
18  
19  // 宠物猫类 
20  class PetCats : public MachinePets {
21  public:
22      PetCats(const string& s) : MachinePets(s) {}
23      string talk() const override {
24          return "miao wu~"; 
25      }
26  };
27  
28  // 宠物狗类
29  class PetDogs : public MachinePets {
30  public:
31      PetDogs(const string& s) : MachinePets(s) {}
32      string talk() const override {
33          return "wang wang~"; 
34      }
35 };

View Code

task3.cpp代码：

 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 }

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运行结果截图：

实验任务4：

film.hpp代码:

 1 #pragma once
 2 #include <iostream>
 3 #include <string>
 4 #include<iomanip>
 5 
 6 using std::ostream;
 7 using std::istream;
 8 using std::string;
 9 using std::setw;
10 
11  class Film {
12  public:
13      // 构造函数
14      Film(const std::string& title = "", const std::string& director = "",
15            const std::string& country = "", int year = 0)
16          : title_(title), director_(director), country_(country), year_(year) {}
17  
18      // 重载输入>>
19      friend std::istream& operator>>(std::istream& is, Film& film) {
20          std::cout << "录入片名：";
21          is >> film.title_;
22          std::cout << "录入导演：";
23          is >> film.director_;
24          std::cout << "录入制片国家/地区：";
25          is >> film.country_;
26          std::cout << "录入上映年份：";
27          is >> film.year_;
28          return is;
29      }
30  
31      // 重载输出<<
32      friend std::ostream& operator<<(std::ostream& os, const Film& film) {
33       
34             os << std::left << setw(15) << film.title_
35                         << setw(15) << film.director_ 
36                         << setw(15) << film.country 
37                         << setw(15) << film.year_;
38          return os;
39      }
40  
41      // 按发行年份升序排序的辅助函数
42      static bool compare_by_year(const Film& a, const Film& b) {
43          return a.year_ < b.year_;
44      }
45  
46  private:
47      std::string title_;      // 片名
48      std::string director_;   // 导演
49      std::string country_;    // 国家/地区
50      int year_;              
51  };

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task4.cpp代码：

 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(), Film::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 }

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运行结果截图：

实验任务5：

Complex.hpp代码：

 1 #ifndef COMPLEX_HPP
 2 #define COMPLEX_HPP
 3 
 4 #include <istream>
 5 #include <ostream>
 6 
 7 template<typename T>
 8 class Complex {
 9 private:
10     T real; 
11     T imag; 
12 
13 public:
14     Complex(T r = 0, T i = 0) : real(r), imag(i) {}
15     T get_real() const { return real; }
16     T get_imag() const { return imag; }
17     void set_real(T r) { real = r; }
18     void set_imag(T i) { imag = i; }
19 
20     // 重载+=
21     Complex& operator+=(const Complex& rhs) {
22         real += rhs.real;
23         imag += rhs.imag;
24         return *this;
25     }
26 
27     // 重载+
28     Complex operator+(const Complex& rhs) const {
29         return Complex(real + rhs.real, imag + rhs.imag);
30     }
31 
32     // 重载==
33     bool operator==(const Complex& rhs) const {
34         return (real == rhs.real) && (imag == rhs.imag);
35     }
36 
37     // 重载>>
38     friend std::istream& operator>>(std::istream& in, Complex& c) {
39         in >> c.real >> c.imag;
40         if (!in) {}
41         return in;
42     }
43 
44     // 重载<<
45     friend std::ostream& operator<<(std::ostream& out, const Complex& c) {
46         if(c.imag > 0){
47             out << c.real << "+" << c.imag << "i";
48         } 
49         else if(c.imag < 0){out << c.real << c.imag << "i";} 
50         else{out << c.real;}
51         return out;
52     }
53 };
54 
55 #endif // COMPLEX_HPP

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task5代码:

 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 }

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实验任务6：

date.hpp:

 1 #pragma once
 2 #ifndef __DATE_H__
 3 #define __DATE_H__
 4 
 5 class Date {    //日期类
 6 private:
 7     int year;        //年
 8     int month;        //月
 9     int day;        //日
10     int totalDays;    //该日期是从公元元年1月1日开始的第几天
11 
12 public:
13     Date(int year, int month, int day);    //用年、月、日构造日期
14     int getYear() const { return year; }
15     int getMonth() const { return month; }
16     int getDay() const { return day; }
17     int getMaxDay() const;        //获得当月有多少天
18     bool isLeapYear() const {    //判断当年是否为闰年
19         return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
20     }
21     void show() const;            //输出当前日期
22     //计算两个日期之间差多少天    
23     int operator - (const Date& date) const {
24         return totalDays - date.totalDays;
25     }
26 };
27 
28 #endif //__DATE_H__

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date.cpp:

 1 //date.cpp
 2 #include "date.h"
 3 #include <iostream>
 4 #include <cstdlib>
 5 using namespace std;
 6 
 7 namespace {    //namespace使下面的定义只在当前文件中有效
 8     //存储平年中某个月1日之前有多少天，为便于getMaxDay函数的实现，该数组多出一项
 9     const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
10 }
11 
12 Date::Date(int year, int month, int day) : year(year), month(month), day(day) {
13     if (day <= 0 || day > getMaxDay()) {
14         cout << "Invalid date: ";
15         show();
16         cout << endl;
17         exit(1);
18     }
19     int years = year - 1;
20     totalDays = years * 365 + years / 4 - years / 100 + years / 400
21         + DAYS_BEFORE_MONTH[month - 1] + day;
22     if (isLeapYear() && month > 2) totalDays++;
23 }
24 
25 int Date::getMaxDay() const {
26     if (isLeapYear() && month == 2)
27         return 29;
28     else
29         return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
30 }
31 
32 void Date::show() const {
33     cout << getYear() << "-" << getMonth() << "-" << getDay();
34 }

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accumulator.hpp:

 1 #pragma once
 2 #ifndef __ACCUMULATOR_H__
 3 #define __ACCUMULATOR_H__
 4 #include "date.h"
 5 
 6 class Accumulator {    //将某个数值按日累加
 7 private:
 8     Date lastDate;    //上次变更数值的时期
 9     double value;    //数值的当前值
10     double sum;        //数值按日累加之和
11 public:
12     //构造函数，date为开始累加的日期，value为初始值
13     Accumulator(const Date& date, double value)
14         : lastDate(date), value(value), sum(0) { }
15 
16     //获得到日期date的累加结果
17     double getSum(const Date& date) const {
18         return sum + value * (date - lastDate);
19     }
20 
21     //在date将数值变更为value
22     void change(const Date& date, double value) {
23         sum = getSum(date);
24         lastDate = date;
25         this->value = value;
26     }
27 
28     //初始化，将日期变为date，数值变为value，累加器清零
29     void reset(const Date& date, double value) {
30         lastDate = date;
31         this->value = value;
32         sum = 0;
33     }
34 };
35 
36 #endif //__ACCUMULATOR_H__

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account.hpp:

 1 #pragma once
 2 #ifndef __ACCOUNT_H__
 3 #define __ACCOUNT_H__
 4 #include "date.h"
 5 #include "accumulator.h"
 6 #include <string>
 7 
 8 class Account { //账户类
 9 private:
10     std::string id;    //帐号
11     double balance;    //余额
12     static double total; //所有账户的总金额
13 protected:
14     //供派生类调用的构造函数，id为账户
15     Account(const Date& date, const std::string& id);
16     //记录一笔帐，date为日期，amount为金额，desc为说明
17     void record(const Date& date, double amount, const std::string& desc);
18     //报告错误信息
19     void error(const std::string& msg) const;
20 public:
21     const std::string& getId() const { return id; }
22     double getBalance() const { return balance; }
23     static double getTotal() { return total; }
24     //存入现金，date为日期，amount为金额，desc为款项说明
25     virtual void deposit(const Date& date, double amount, const std::string& desc) = 0;
26     //取出现金，date为日期，amount为金额，desc为款项说明
27     virtual void withdraw(const Date& date, double amount, const std::string& desc) = 0;
28     //结算（计算利息、年费等），每月结算一次，date为结算日期
29     virtual void settle(const Date& date) = 0;
30     //显示账户信息
31     virtual void show() const;
32 };
33 
34 class SavingsAccount : public Account { //储蓄账户类
35 private:
36     Accumulator acc;    //辅助计算利息的累加器
37     double rate;        //存款的年利率
38 public:
39     //构造函数
40     SavingsAccount(const Date& date, const std::string& id, double rate);
41     double getRate() const { return rate; }
42     virtual void deposit(const Date& date, double amount, const std::string& desc);
43     virtual void withdraw(const Date& date, double amount, const std::string& desc);
44     virtual void settle(const Date& date);
45 };
46 
47 class CreditAccount : public Account { //信用账户类
48 private:
49     Accumulator acc;    //辅助计算利息的累加器
50     double credit;        //信用额度
51     double rate;        //欠款的日利率
52     double fee;            //信用卡年费
53 
54     double getDebt() const {    //获得欠款额
55         double balance = getBalance();
56         return (balance < 0 ? balance : 0);
57     }
58 public:
59     //构造函数
60     CreditAccount(const Date& date, const std::string& id, double credit, double rate, double fee);
61     double getCredit() const { return credit; }
62     double getRate() const { return rate; }
63     double getFee() const { return fee; }
64     double getAvailableCredit() const {    //获得可用信用
65         if (getBalance() < 0)
66             return credit + getBalance();
67         else
68             return credit;
69     }
70     virtual void deposit(const Date& date, double amount, const std::string& desc);
71     virtual void withdraw(const Date& date, double amount, const std::string& desc);
72     virtual void settle(const Date& date);
73     virtual void show() const;
74 };
75 
76 #endif //__ACCOUNT_H__

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account.cpp:

 1 #include "account.h"
 2 #include <cmath>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 double Account::total = 0;
 7 
 8 //Account类的实现
 9 Account::Account(const Date& date, const string& id)
10     : id(id), balance(0) {
11     date.show();
12     cout << "\t#" << id << " created" << endl;
13 }
14 
15 void Account::record(const Date& date, double amount, const string& desc) {
16     amount = floor(amount * 100 + 0.5) / 100;    //保留小数点后两位
17     balance += amount;
18     total += amount;
19     date.show();
20     cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
21 }
22 
23 void Account::show() const {
24     cout << id << "\tBalance: " << balance;
25 }
26 
27 void Account::error(const string& msg) const {
28     cout << "Error(#" << id << "): " << msg << endl;
29 }
30 
31 //SavingsAccount类相关成员函数的实现
32 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate)
33     : Account(date, id), rate(rate), acc(date, 0) { }
34 
35 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
36     record(date, amount, desc);
37     acc.change(date, getBalance());
38 }
39 
40 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
41     if (amount > getBalance()) {
42         error("not enough money");
43     }
44     else {
45         record(date, -amount, desc);
46         acc.change(date, getBalance());
47     }
48 }
49 
50 void SavingsAccount::settle(const Date& date) {
51     if (date.getMonth() == 1) {    //每年的一月计算一次利息
52         double interest = acc.getSum(date) * rate
53             / (date - Date(date.getYear() - 1, 1, 1));
54         if (interest != 0)
55             record(date, interest, "interest");
56         acc.reset(date, getBalance());
57     }
58 }
59 
60 //CreditAccount类相关成员函数的实现
61 CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee)
62     : Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) { }
63 
64 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
65     record(date, amount, desc);
66     acc.change(date, getDebt());
67 }
68 
69 void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
70     if (amount - getBalance() > credit) {
71         error("not enough credit");
72     }
73     else {
74         record(date, -amount, desc);
75         acc.change(date, getDebt());
76     }
77 }
78 
79 void CreditAccount::settle(const Date& date) {
80     double interest = acc.getSum(date) * rate;
81     if (interest != 0)
82         record(date, interest, "interest");
83     if (date.getMonth() == 1)
84         record(date, -fee, "annual fee");
85     acc.reset(date, getDebt());
86 }
87 
88 void CreditAccount::show() const {
89     Account::show();
90     cout << "\tAvailable credit:" << getAvailableCredit();
91 }

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8_8.cpp:

 1 //8_8.cpp
 2 #include "account.h"
 3 #include <iostream>
 4 using namespace std;
 5 
 6 int main() {
 7     Date date(2008, 11, 1);    //起始日期
 8     //建立几个账户
 9     SavingsAccount sa1(date, "S3755217", 0.015);
10     SavingsAccount sa2(date, "02342342", 0.015);
11     CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);
12     Account* accounts[] = { &sa1, &sa2, &ca };
13     const int n = sizeof(accounts) / sizeof(Account*);    //账户总数
14 
15     cout << "(d)deposit (w)withdraw (s)show (c)change day (n)next month (e)exit" << endl;
16     char cmd;
17     do {
18         //显示日期和总金额
19         date.show();
20         cout << "\tTotal: " << Account::getTotal() << "\tcommand> ";
21 
22         int index, day;
23         double amount;
24         string desc;
25 
26         cin >> cmd;
27         switch (cmd) {
28         case 'd':    //存入现金
29             cin >> index >> amount;
30             getline(cin, desc);
31             accounts[index]->deposit(date, amount, desc);
32             break;
33         case 'w':    //取出现金
34             cin >> index >> amount;
35             getline(cin, desc);
36             accounts[index]->withdraw(date, amount, desc);
37             break;
38         case 's':    //查询各账户信息
39             for (int i = 0; i < n; i++) {
40                 cout << "[" << i << "] ";
41                 accounts[i]->show();
42                 cout << endl;
43             }
44             break;
45         case 'c':    //改变日期
46             cin >> day;
47             if (day < date.getDay())
48                 cout << "You cannot specify a previous day";
49             else if (day > date.getMaxDay())
50                 cout << "Invalid day";
51             else
52                 date = Date(date.getYear(), date.getMonth(), day);
53             break;
54         case 'n':    //进入下个月
55             if (date.getMonth() == 12)
56                 date = Date(date.getYear() + 1, 1, 1);
57             else
58                 date = Date(date.getYear(), date.getMonth() + 1, 1);
59             for (int i = 0; i < n; i++)
60                 accounts[i]->settle(date);
61             break;
62         }
63     } while (cmd != 'e');
64     return 0;
65 }

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运行结果截图：

调整:

重载了运算符，使计算过程更加方便，使用了继承和多态性来扩展功能，每种账户类型可以有自己的计算方式和特殊功能。

优化了用户界面的设计，使得用户可以更方便地输入和查询账户信息。

改进方案:

可以考虑引入文件操作，将账户信息保存到文件中，以便在程序重启后能够恢复之前的数据，确保在多个线程同时访问和修改账户信息时，数据的一致性不会受到破坏。

posted on 2024-12-08 18:27 rrrrrrrr00000 阅读(5) 评论(0) 编辑收藏举报