实验4 类的组成、继承、模板类、标准库

任务二：

代码：

task2.cpp:

 1 #include "GradeCalc.hpp"
 2 #include <iomanip>
 3 
 4 void test() {
 5     int n;
 6     cout << "输入班级人数: ";
 7     cin >> n;
 8 
 9     GradeCalc c1("OOP", n);
10 
11     cout << "录入成绩: " << endl;;
12     c1.input();
13     cout << "输出成绩: " << endl;
14     c1.output();
15 
16     cout << string(20, '*') + "课程成绩信息"  + string(20, '*') << endl;
17     c1.info();
18 }
19 
20 int main() {
21     test();
22 }

View Code

GradeCalc.hpp:

  1 #include <iostream>
  2 #include <vector>
  3 #include <string>
  4 #include <algorithm>
  5 #include <numeric>
  6 #include <iomanip>
  7 
  8 using std::vector;
  9 using std::string;
 10 using std::cin;
 11 using std::cout;
 12 using std::endl;
 13 
 14 class GradeCalc: public vector<int> {
 15 public:
 16     GradeCalc(const string &cname, int size);      
 17     void input();                             // 录入成绩
 18     void output() const;                      // 输出成绩
 19     void sort(bool ascending = false);        // 排序 (默认降序)
 20     int min() const;                          // 返回最低分
 21     int max() const;                          // 返回最高分
 22     float average() const;                    // 返回平均分
 23     void info();                              // 输出课程成绩信息 
 24 
 25 private:
 26     void compute();     // 成绩统计
 27 
 28 private:
 29     string course_name;     // 课程名
 30     int n;                  // 课程人数
 31     vector<int> counts = vector<int>(5, 0);      // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]
 32     vector<double> rates = vector<double>(5, 0); // 保存各分数段比例 
 33 };
 34 
 35 GradeCalc::GradeCalc(const string &cname, int size): course_name{cname}, n{size} {}   
 36 
 37 void GradeCalc::input() {
 38     int grade;
 39 
 40     for(int i = 0; i < n; ++i) {
 41         cin >> grade;
 42         this->push_back(grade);
 43     } 
 44 }  
 45 
 46 void GradeCalc::output() const {
 47     for(auto ptr = this->begin(); ptr != this->end(); ++ptr)
 48         cout << *ptr << " ";
 49     cout << endl;
 50 } 
 51 
 52 void GradeCalc::sort(bool ascending) {
 53     if(ascending)
 54         std::sort(this->begin(), this->end());
 55     else
 56         std::sort(this->begin(), this->end(), std::greater<int>());
 57 }  
 58 
 59 int GradeCalc::min() const {
 60     return *std::min_element(this->begin(), this->end());
 61 }  
 62 
 63 int GradeCalc::max() const {
 64     return *std::max_element(this->begin(), this->end());
 65 }    
 66 
 67 float GradeCalc::average() const {
 68     return std::accumulate(this->begin(), this->end(), 0) * 1.0 / n;
 69 }   
 70 
 71 void GradeCalc::compute() {
 72     for(int grade: *this) {
 73         if(grade < 60)
 74             counts.at(0)++;
 75         else if(grade >= 60 && grade < 70)
 76             counts.at(1)++;
 77         else if(grade >= 70 && grade < 80)
 78             counts.at(2)++;
 79         else if(grade >= 80 && grade < 90)
 80             counts.at(3)++;
 81         else if(grade >= 90)
 82             counts.at(4)++;
 83     }
 84 
 85     for(int i = 0; i < rates.size(); ++i)
 86         rates.at(i) = counts.at(i) * 1.0 / n;
 87 }
 88 
 89 void GradeCalc::info()  {
 90     cout << "课程名称:\t" << course_name << endl;
 91     cout << "排序后成绩: \t";
 92     sort();  output();
 93     cout << "最高分:\t" << max() << endl;
 94     cout << "最低分:\t" << min() << endl;
 95     cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
 96     
 97     compute();  // 统计各分数段人数、比例
 98 
 99     vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
100     for(int i = tmp.size()-1; i >= 0; --i)
101         cout << tmp[i] << "\t: " << counts[i] << "人\t" 
102              << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl; 
103 }

View Code

运行截图：

问题1：成绩存储在Gradecalc类的内部，由于Gradecalc派生自 std::vector<int>，它直接继承了这个向量，用于存储成绩。派生类中的方法 sort, min, max, average, 和 output 都是通过 this 指针来访问成绩的。在 C++ 中，当一个对象的方法被调用时，this 指针指向调用该方法的对象。由于 GradeCalc 派生自 std::vector<int>，这些方法可以直接使用 this 指针来访问和操作存储的成绩（即 std::vector<int> 中的元素）。input 方法通过 this->push_back(grade) 将成绩添加到对象中。由于 GradeCalc 派生自 std::vector<int>，它继承了 push_back 方法，该方法用于在向量的末尾添加一个元素。因此，input 方法通过调用 push_back 将每个输入的成绩添加到 GradeCalc 对象内部存储的向量中。

问题2：

这里的分母 n 代表课程人数，即成绩的总数。关于乘以1.0的部分，这里主要是为了确保计算结果的类型为浮点数。如果去掉乘以1.0的代码，重新编译、运行，结果确实会受到影响。具体来说，平均分将不再是一个浮点数，而是一个整数，因为整数除法会丢失小数部分。

问题3：

目前 input 方法只是简单地接收用户输入的成绩，并没有对输入进行合法性检查。在实际应用中，应该增加输入验证，确保用户输入的是有效的整数成绩，并且成绩在合理的范围内（如0到100之间）。

任务三：

代码：

GradeCalc.hpp：

  1 #include <iostream>
  2 #include <vector>
  3 #include <string>
  4 #include <algorithm>
  5 #include <numeric>
  6 #include <iomanip>
  7 
  8 using std::vector;
  9 using std::string;
 10 using std::cin;
 11 using std::cout;
 12 using std::endl;
 13 
 14 class GradeCalc {
 15 public:
 16     GradeCalc(const string &cname, int size);      
 17     void input();                             // 录入成绩
 18     void output() const;                      // 输出成绩
 19     void sort(bool ascending = false);        // 排序 (默认降序)
 20     int min() const;                          // 返回最低分
 21     int max() const;                          // 返回最高分
 22     float average() const;                    // 返回平均分
 23     void info();                              // 输出课程成绩信息 
 24 
 25 private:
 26     void compute();     // 成绩统计
 27 
 28 private:
 29     string course_name;     // 课程名
 30     int n;                  // 课程人数
 31     vector<int> grades;     // 课程成绩
 32     vector<int> counts = vector<int>(5, 0);      // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]
 33     vector<double> rates = vector<double>(5, 0); // 保存各分数段比例 
 34 };
 35 
 36 GradeCalc::GradeCalc(const string &cname, int size): course_name{cname}, n{size} {}   
 37 
 38 void GradeCalc::input() {
 39     int grade;
 40 
 41     for(int i = 0; i < n; ++i) {
 42         cin >> grade;
 43         grades.push_back(grade);
 44     } 
 45 }  
 46 
 47 void GradeCalc::output() const {
 48     for(int grade: grades)
 49         cout << grade << " ";
 50     cout << endl;
 51 } 
 52 
 53 void GradeCalc::sort(bool ascending) {
 54     if(ascending)
 55         std::sort(grades.begin(), grades.end());
 56     else
 57         std::sort(grades.begin(), grades.end(), std::greater<int>());
 58         
 59 }  
 60 
 61 int GradeCalc::min() const {
 62     return *std::min_element(grades.begin(), grades.end());
 63 }  
 64 
 65 int GradeCalc::max() const {
 66     return *std::max_element(grades.begin(), grades.end());
 67 }    
 68 
 69 float GradeCalc::average() const {
 70     return std::accumulate(grades.begin(), grades.end(), 0) * 1.0 / n;
 71 }   
 72 
 73 void GradeCalc::compute() {
 74     for(int grade: grades) {
 75         if(grade < 60)
 76             counts.at(0)++;
 77         else if(grade >= 60 && grade < 70)
 78             counts.at(1)++;
 79         else if(grade >= 70 && grade < 80)
 80             counts.at(2)++;
 81         else if(grade >= 80 && grade < 90)
 82             counts.at(3)++;
 83         else if(grade >= 90)
 84             counts.at(4)++;
 85     }
 86 
 87     for(int i = 0; i < rates.size(); ++i)
 88         rates.at(i) = counts.at(i) *1.0 / n;
 89 }
 90 
 91 void GradeCalc::info()  {
 92     cout << "课程名称:\t" << course_name << endl;
 93     cout << "排序后成绩: \t";
 94     sort();  output();
 95     cout << "最高分:\t" << max() << endl;
 96     cout << "最低分:\t" << min() << endl;
 97     cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
 98     
 99     compute();  // 统计各分数段人数、比例
100 
101     vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
102     for(int i = tmp.size()-1; i >= 0; --i)
103         cout << tmp[i] << "\t: " << counts[i] << "人\t" 
104              << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl; 
105 }

View Code

task3.cpp：

#include "GradeCalc.hpp"
#include <iomanip>

void test() {
    int n;
    cout << "输入班级人数: ";
    cin >> n;

    GradeCalc c1("OOP", n);

    cout << "录入成绩: " << endl;;
    c1.input();
    cout << "输出成绩: " << endl;
    c1.output();

    cout << string(20, '*') + "课程成绩信息"  + string(20, '*') << endl;
    c1.info();
}

int main() {
    test();
}

运行截图：

问题1：

在GradeCalc类中，成绩被存储在私有成员变量vector<int> grades中。这个成员变量是一个整数向量，用于保存课程的所有成绩。

组合类方法sort, min, max, average, output都需要访问这些成绩，它们通过成员函数指针来访问类的成员变量。

问题2：

通过继承和多态等机制，我们可以轻松地扩展现有类的功能或创建新的类来满足新的需求。

任务4：

代码：

task4_1.cpp:

 1 #include <iostream>
 2 #include <string>
 3 #include <limits>
 4 
 5 using namespace std;
 6 
 7 void test1() {
 8     string s1, s2;
 9     cin >> s1 >> s2;  // cin: 从输入流读取字符串, 碰到空白符(空格/回车/Tab)即结束
10     cout << "s1: " << s1 << endl;
11     cout << "s2: " << s2 << endl;
12 }
13 
14 void test2() {
15     string s1, s2;
16     getline(cin, s1);  // getline(): 从输入流中提取字符串，直到遇到换行符
17     getline(cin, s2);
18     cout << "s1: " << s1 << endl;
19     cout << "s2: " << s2 << endl;
20 }
21 
22 void test3() {
23     string s1, s2;
24     getline(cin, s1, ' '); //从输入流中提取字符串，直到遇到指定分隔符
25     getline(cin, s2);
26     cout << "s1: " << s1 << endl;
27     cout << "s2: " << s2 << endl;
28 }
29 
30 int main() {
31     cout << "测试1: 使用标准输入流对象cin输入字符串" << endl;
32     test1();
33     cout << endl;
34 
35     cin.ignore(numeric_limits<streamsize>::max(), '\n');
36 
37     cout << "测试2: 使用函数getline()输入字符串" << endl;
38     test2();
39     cout << endl;
40 
41     cout << "测试3: 使用函数getline()输入字符串, 指定字符串分隔符" << endl;
42     test3();
43 }

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运行截图：

问题1：

当程序运行到test2()时，由于之前test1()的输入后留下了一个换行符在输入缓冲区中，getline(cin, s1);会立即读取到这个换行符并结束读取，因此s1将为空字符串。随后，getline(cin, s2);会等待用户输入下一个字符串，并将其赋值给s2。

task4_2.cpp:

 1 #include <iostream>
 2 #include <string>
 3 #include <vector>
 4 #include <limits>
 5 
 6 using namespace std;
 7 
 8 void output(const vector<string> &v) {
 9     for(auto &s: v)
10         cout << s << endl;
11 }
12 
13 void test() {
14     int n;
15     while(cout << "Enter n: ", cin >> n) {
16         vector<string> v1;
17 
18         for(int i = 0; i < n; ++i) {
19             string s;
20             cin >> s;
21             v1.push_back(s);
22         }
23 
24         cout << "output v1: " << endl;
25         output(v1); 
26         cout << endl;
27     }
28 }
29 
30 int main() {
31     cout << "测试: 使用cin多组输入字符串" << endl;
32     test();
33 }

View Code

运行截图：

task4_3.cpp:

 1 #include <iostream>
 2 #include <string>
 3 #include <vector>
 4 #include <limits>
 5 
 6 using namespace std;
 7 
 8 void output(const vector<string> &v) {
 9     for(auto &s: v)
10         cout << s << endl;
11 }
12 
13 void test() {
14     int n;
15     while(cout << "Enter n: ", cin >> n) {
16         cin.ignore(numeric_limits<streamsize>::max(), '\n');
17 
18         vector<string> v2;
19 
20         for(int i = 0; i < n; ++i) {
21             string s;
22             getline(cin, s);
23             v2.push_back(s);
24         }
25         cout << "output v2: " << endl;
26         output(v2); 
27         cout << endl;
28     }
29 }
30 
31 int main() {
32     cout << "测试: 使用函数getline()多组输入字符串" << endl;
33     test();
34 }

View Code

运行截图：

问题2：

这行代码的作用是忽略输入缓冲区中直到下一个换行符（\n）的所有字符。这通常用于清除输入缓冲区中残留的换行符或其他不需要的字符，以避免它们干扰后续的输入操作。

任务五：

代码：

task5.cpp：

 1 #include "grm.hpp"
 2 #include <iostream>
 3 
 4 using std::cout;
 5 using std::endl;
 6 
 7 void test1() {
 8     GameResourceManager<float> HP_manager(99.99);
 9     cout << "当前生命值: " << HP_manager.get() << endl;
10     HP_manager.update(9.99);
11     cout << "增加9.99生命值后, 当前生命值: " << HP_manager.get() << endl;
12     HP_manager.update(-999.99);
13     cout <<"减少999.99生命值后, 当前生命值: " << HP_manager.get() << endl;
14 }
15 
16 void test2() {
17     GameResourceManager<int> Gold_manager(100);
18     cout << "当前金币数量: " << Gold_manager.get() << endl;
19     Gold_manager.update(50);
20     cout << "增加50个金币后, 当前金币数量: " << Gold_manager.get() << endl;
21     Gold_manager.update(-99);
22     cout <<"减少99个金币后, 当前金币数量: " << Gold_manager.get() << endl;
23 }
24 
25 
26 int main() {
27     cout << "测试1: 用float类型对类模板GameResourceManager实例化" << endl;
28     test1();
29     cout << endl;
30 
31     cout << "测试2: 用int类型对类模板GameResourceManager实例化" << endl;
32     test2();
33 }

View Code

grm.hpp：

 1 #include<iostream>
 2 using namespace std;
 3 template<typename T>
 4 class GameResourceManager{
 5     private:
 6         T resource;
 7     public:
 8         GameResourceManager(T x);
 9         T get();
10         void update(T x1);
11 };
12 template<typename T>
13 GameResourceManager<T>::GameResourceManager(T x):resource(x){}
14 template<typename T>
15 T GameResourceManager<T>::get()
16 {
17     return resource;
18 }
19 template<typename T>
20 void GameResourceManager<T>::update(T x1)
21 {
22     resource+=x1;
23     if(resource<0)
24     resource=0;
25 }

View Code

运行截图：

任务六：

代码：

info.hpp：

 1 #include<iostream>
 2 #include<string>
 3 using namespace std;
 4 class info{
 5     private:
 6         string nickname;
 7         string contact;
 8         string city;
 9         int n;
10     public:
11         info(string name,string node,string cs,int num);
12         void display();
13 };
14 info::info(string name,string node,string cs,int num):nickname(name),contact(node),city(cs),n(num){
15 }
16 void info::display()
17 {
18     cout<<"昵称:    \t"<<nickname<<endl;
19     cout<<"联系方式:\t"<<contact<<endl;
20     cout<<"所在城市:\t"<<city<<endl;
21     cout<<"预订人数:\t"<<n<<endl;
22 }

View Code

task6.cpp：

#include <iostream>
#include <vector>
#include <string>
#include "info.hpp"

using namespace std;
const int capacity = 100;

int main() {
    vector<info> audiences;
    int current = capacity;
    string nickname, contact, city;
    int n;

    cout << "请输入预约信息（按Ctrl+Z停止输入或人数达到上限）：\n";

    while (true) {
        cout << "昵称: ";
        cin >> nickname;
        cout << "联系方式 (email 或 手机号): ";
        cin >> contact;
        cout << "所在城市: ";
        cin >> city;
        cout << "预定参加人数: ";
        cin >> n;

        if (n > current) {
            cout<<"对不起,只剩下"<<current<<"个座位"<<endl; 
            cout << "预定人数超过剩余容量，请输入q退出预定或输入u更新预定信息。\n";
            char choice;
            cout<<"你的选择:";
            cin >> choice;
            if (choice == 'q') {
                break;
            } 
            else if (choice == 'u') {
                cout<<"请重新输入预订信息:";
                continue; 
            } 
            else {
                cout << "无效选择，请输入q或u。\n";
                continue;
            }
        }
         else {
            audiences.emplace_back(nickname, contact, city, n);
            current-= n;

            if (current <= 0) {
                break;
            }
        }
    }

    cout << "\n截至目前,一共有"<<100-current<<"位听众预约。预约听众信息如下：\n";
    for ( auto& info : audiences) {
        info.display();
        cout << "\n";
    }

    return 0;
}

运行截图：

任务七：

代码：

task7.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);

    sa1.deposit(Date(2008, 11, 5), 5000, "salary");
    ca.withdraw(Date(2008, 11, 15), 2000, "buy a cell");
    sa2.deposit(Date(2008, 11, 25), 10000, "sell stock 0323");

    ca.settle(Date(2008, 12, 1));

    ca.deposit(Date(2008, 12, 1), 2016, "repay the credit");
    sa1.deposit(Date(2008, 12, 5), 5500, "salary");

    sa1.settle(Date(2009, 1, 1));
    sa2.settle(Date(2009, 1, 1));
    ca.settle(Date(2009, 1, 1));

    cout << endl;
    sa1.show(); cout << endl;
    sa2.show(); cout << endl;
    ca.show(); cout << endl;
    cout << "Total:" << Account::getTotal() << endl;

    return 0;
}

data.h：

 1 #ifndef __DATE_H__
 2 #define __DATE_H__
 3 
 4 class Date {
 5 private:
 6     int year;
 7     int month;
 8     int day;
 9     int totalDays;
10 public:
11     Date(int year, int month, int day);
12     int getYear() const { return year; }
13     int getMonth() const { return month; }
14     int getDay() const { return day; }
15     int getMaxDay() const;
16     bool isLeapYear() const {
17         return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
18     }
19     void show() const;
20 
21     int distance(const Date& date) const {
22         return totalDays - date.totalDays;
23     }
24 };

View Code

 1 #include "date.h"
 2 #include <iostream>
 3 #include <cstdlib>
 4 using namespace std;
 5 namespace {
 6     const int DAYS_BEFORE_MONTH[] = { 0,31,59,90,120,151,181,212,243,273,304,334,365 };
 7 }
 8 
 9 Date::Date(int year, int month, int day) : year(year), month(month), day(day) {
10     if (day <= 0 || day > getMaxDay()) {
11         cout << "Invalid date:";
12         show();
13         cout << endl;
14         exit(1);
15     }
16     int years = year - 1;
17     totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day;
18     if (isLeapYear() && month > 2) totalDays++;
19 }
20 
21 int Date::getMaxDay() const {
22     if (isLeapYear() && month == 2)
23         return 29;
24     else
25         return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
26 }
27 
28 void Date::show() const {
29     cout << getYear() << "-" << getMonth() << "-" << getDay();
30 }

View Code

 1 #pragma once
 2 #ifndef ACCUMULATOR_H
 3 #define ACCUMULATOR_H
 4 
 5 #include "date.h"
 6 
 7 class Accumulator {
 8 private:
 9     Date lastDate;
10     double value;
11     double sum;
12 
13 public:
14     Accumulator(const Date& date, double value) : lastDate(date), value(value), sum(0) {
15     }
16 
17     double getSum(const Date& date) const {
18         return sum + value * date.distance(lastDate);
19     }
20 
21     void change(const Date& date, double value) {
22         sum = getSum(date);
23         lastDate = date;
24         this->value = value;
25     }
26 
27     void reset(const Date& date, double value) {
28         lastDate = date;
29         this->value = value;
30         sum = 0;
31     }
32 };

View Code

#pragma once
#ifndef ACCOUNT_H
#define ACCOUNT_H

#include "date.h"
#include "accumulator.h"
#include <string>

class Account {
private:
    std::string id;
    double balance;
    static double total;

protected:
    Account(const Date& date, const std::string& id);
    void record(const Date& date, double amount, const std::string& desc);
    void error(const std::string& msg) const;

public:
    const std::string& getId() const;
    double getBalance() const;
    static double getTotal();

    void show() const;
};

class SavingsAccount : public Account {
private:
    Accumulator acc;
    double rate;

public:
    SavingsAccount(const Date& date, const std::string& id, double rate);
    double getRate() const;

    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);
};

class CreditAccount : public Account {
private:
    Accumulator acc;
    double credit;
    double rate;
    double fee;
    double getDebt() const;

public:
    CreditAccount(const Date& date, const std::string& id, double credit, double rate, double fee);
    double getCredit() const;
    double getRate() const;
    double getAvailableCredit() const;

    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;
};

 1 #include "account.h"
 2 #include <cmath>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 double Account::total = 0;
 7 
 8 Account::Account(const Date& date, const string& id) : id(id), balance(0) {
 9     date.show(); 
10     cout << "\t#" << id << " created" << endl;
11 }
12 
13 void Account::record(const Date& date, double amount, const string& desc) {
14     amount = floor(amount * 100 + 0.5) / 100; // 四舍五入到两位小数
15     balance += amount;
16     total += amount;
17     date.show();
18     cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
19 }
20 
21 void Account::show() const {
22     cout << id << "\tBalance:" << balance;
23 }
24 
25 void Account::error(const string& msg) const {
26     cout << "Error(#" << id << "):" << msg << endl;
27 }
28 
29 SavingsAccount::SavingsAccount(const Date& date, const string& id, double rate)
30     : Account(date, id), rate(rate), acc(date, 0) {}
31 
32 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
33     record(date, amount, desc);
34     acc.change(date, getBalance());
35 }
36 
37 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
38     if (amount > getBalance()) {
39         error("not enough money");
40     } else {
41         record(date, -amount, desc);
42         acc.change(date, getBalance());
43     }
44 }
45 
46 void SavingsAccount::settle(const Date& date) {
47     double interest = acc.getSum(date) * rate / date.distance(Date(date.getYear() - 1, 1, 1));
48     if (interest != 0) record(date, interest, "interest");
49     acc.reset(date, getBalance());
50 }
51 
52 CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee)
53     : Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) {}
54 
55 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
56     record(date, amount, desc);
57     acc.change(date, getDebt());
58 }
59 
60 void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
61     if (amount - getBalance() > credit) {
62         error("not enough credit");
63     } else {
64         record(date, -amount, desc);
65         acc.change(date, getDebt());
66     }
67 }
68 
69 void CreditAccount::settle(const Date& date) {
70     double interest = acc.getSum(date) * rate;
71     if (interest != 0) record(date, interest, "interest");
72     if (date.getMonth() == 1)
73         record(date, -fee, "annual fee");
74     acc.reset(date, getDebt());
75 }
76 
77 void CreditAccount::show() const {
78     Account::show();
79     cout << "\tAvailable credit:" << getAvailableCredit();
80 }

View Code

运行截图：

posted @ 2024-11-24 11:39 白鸽nm海鸥阅读(4) 评论(0) 编辑收藏举报

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