1.实验任务1

 1 #include <iostream>
 2 
 3 using std::cout;
 4 using std::endl;
 5 
 6 // 类A的定义
 7 class A {
 8 public:
 9     A(int x0, int y0);
10     void display() const;
11 
12 private:
13     int x, y;
14 };
15 
16 A::A(int x0, int y0): x{x0}, y{y0} {
17 }
18 
19 void A::display() const {
20     cout << x << ", " << y << endl;
21 }
22 
23 // 类B的定义
24 class B {
25 public:
26     B(double x0, double y0);
27     void display() const;
28 
29 private:
30     double x, y;
31 };
32 
33 B::B(double x0, double y0): x{x0}, y{y0} {
34 }
35 
36 void B::display() const {
37     cout << x << ", " << y << endl;
38 }
39 
40 void test() {
41     cout << "测试类A: " << endl;
42     A a(3, 4);
43     a.display();
44 
45     cout << "\n测试类B: " << endl;
46     B b(3.2, 5.6);
47     b.display();
48 }
49 
50 int main() {
51     test();
52 }

 1 #include <iostream>
 2 #include <string>
 3 
 4 using std::cout;
 5 using std::endl;
 6 using std::string;
 7 
 8 // 定义类模板
 9 template<typename T>
10 class X{
11 public:
12     X(T x0, T y0);
13     void display();
14 
15 private:
16     T x, y;
17 };
18 
19 template<typename T>
20 X<T>::X(T x0, T y0): x{x0}, y{y0} {
21 }
22 
23 template<typename T>
24 void X<T>::display() {
25     cout << x << ", " << y << endl;
26 }
27 
28 
29 void test() {
30     cout << "测试1: 类模板X中的抽象类型T用int实例化" << endl;
31     X<int> x1(3, 4);
32     x1.display();
33     
34     cout << endl;
35 
36     cout << "测试2: 类模板X中的抽象类型T用double实例化" << endl;
37     X<double> x2(3.2, 5.6);
38     x2.display();
39 
40     cout << endl;
41 
42     cout << "测试3: 类模板X中的抽象类型T用string实例化" << endl;
43     X<string> x3("hello", "oop");
44     x3.display();
45 }
46 
47 int main() {
48     test();
49 }

 

 1 #include <complex>
 2 #include <vector>
 3 #include <array>
 4 
 5 int main() {
 6     using namespace std;
 7     
 8     complex<double> x1(5,3);        // complex类模板，特化到double类型
 9     vector<int> x2{1, 9, 8, 4};        // vector类模板，特化到int类型
10     array<int, 4> x3{1,9, 8, 4};    // array类模板，特化到int类型
11     // 其它略
12 }

 

2.实验任务2

  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 } 
 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 }

问题1：存储在vector<int>中，派生类方法sort, min, max, average, output通过this指针访问。input 方法通过 this->push_back(grade) 接口将成绩存入对象。

问题2：计算平均值。去掉*1.0后，重新编译和运行，代码很可能会得到错误的结果。*1.0后确保计算结果为浮点数，从而避免求平均值时小数部分的丢失。

问题3：input输入的数据没有合法判定。

3.实验任务3

  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 } 
 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 }

 

问题1：

在组合类GradeCalc的定义中，成绩存储在私有成员变量vector<int> grades中。

组合类方法sort, min, max, average, output都需要访问这些成绩，它们通过直接访问grades向量来实现。

4.实验任务4

#include <iostream>
#include <string>
#include <limits>

using namespace std;

void test1() {
    string s1, s2;
    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
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

void test2() {
    string s1, s2;
    getline(cin, s1);  // getline(): 从输入流中提取字符串，直到遇到换行符
    getline(cin, s2);
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

void test3() {
    string s1, s2;
    getline(cin, s1, ' '); //从输入流中提取字符串，直到遇到指定分隔符
    getline(cin, s2);
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
}

int main() {
    cout << "测试1: 使用标准输入流对象cin输入字符串" << endl;
    test1();
    cout << endl;

    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    cout << "测试2: 使用函数getline()输入字符串" << endl;
    test2();
    cout << endl;

    cout << "测试3: 使用函数getline()输入字符串, 指定字符串分隔符" << endl;
    test3();
}

问题1：清空缓冲区的内容，消除上一次输入对下一次输入的影响。

#include <iostream>
#include <string>
#include <vector>
#include <limits>

using namespace std;

void output(const vector<string> &v) {
    for(auto &s: v)
        cout << s << endl;
}

void test() {
    int n;
    while(cout << "Enter n: ", cin >> n) {
        vector<string> v1;

        for(int i = 0; i < n; ++i) {
            string s;
            cin >> s;
            v1.push_back(s);
        }

        cout << "output v1: " << endl;
        output(v1); 
        cout << endl;
    }
}

int main() {
    cout << "测试: 使用cin多组输入字符串" << endl;
    test();
}

#include <iostream>
#include <string>
#include <vector>
#include <limits>

using namespace std;

void output(const vector<string> &v) {
    for(auto &s: v)
        cout << s << endl;
}

void test() {
    int n;
    while(cout << "Enter n: ", cin >> n) {
        cin.ignore(numeric_limits<streamsize>::max(), '\n');

        vector<string> v2;

        for(int i = 0; i < n; ++i) {
            string s;
            getline(cin, s);
            v2.push_back(s);
        }
        cout << "output v2: " << endl;
        output(v2); 
        cout << endl;
    }
}

int main() {
    cout << "测试: 使用函数getline()多组输入字符串" << endl;
    test();
}

问题2：清空缓冲区的内容，消除上一次输入对下一次输入的影响。

5.实验任务5

 1 #include<iostream>
 2 using namespace std;
 3 template<typename T>
 4 class GameResourceManager {
 5 public:
 6     GameResourceManager(T hp):HP(hp){}
 7     T get(){
 8         return HP;
 9     }
10     void update(T data){
11         HP+=data;
12     }
13 private:
14     T HP; 
15 };
 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 }

6.实验任务6

 

#ifndef INFO_HPP
#define INFO_HPP

#include <iostream>
#include <string>

class Info {
private:
    std::string nickname;
    std::string contact;
    std::string city;
    int n;

public:
    Info(std::string nickname, std::string contact, std::string city, int n);
    void display() const;
};

#endif
#include "info.hpp"
Info::Info(std::string nickname, std::string contact, std::string city, int n)
    : nickname(nickname), contact(contact), city(city), n(n) {}
void Info::display() const {
    std::cout << "昵称: " << nickname << std::endl;
    std::cout << "联系方式: " << contact << std::endl;
    std::cout << "所在城市: " << city << std::endl;
    std::cout << "预定参加人数: " << n << std::endl;
}
#include <iostream>
#include <vector>
#include "info.hpp"
const int capacity = 100;
int main() {
    std::vector<Info> audience_list;
    int current_capacity = 0;
    std::cout << "开始录入用户预约信息：" << std::endl;
    while (true) {
        if (current_capacity >= capacity) {
            std::cout << "场地已满，无法继续预约。" << std::endl;
            break;
        }
        std::string nickname, contact, city;
        int num_attendees;
        std::cout << "昵称：";
        std::cin >> nickname;

        if (nickname == "q") {
            break;
        }
        std::cout << "联系方式：";
        std::cin >> contact;
        std::cout << "所在城市：";
        std::cin >> city;
        std::cout << "预定参加人数：";
        std::cin >> num_attendees;
        if (current_capacity + num_attendees > capacity) {
            std::cout << "超出场地剩余容量，剩余容量：" << (capacity - current_capacity) << std::endl;
            std::cout << "输入'u'更新预约信息，输入'q'退出：";
            std::string choice;
            std::cin >> choice;
            if (choice == "q") {
                break;
            } else if (choice == "u") {
                std::cout << "重新输入预约信息：" << std::endl;
                std::cout << "昵称：";
                std::cin >> nickname;
                std::cout << "联系方式：";
                std::cin >> contact;
                std::cout << "所在城市：";
                std::cin >> city;
                std::cout << "预定参加人数：";
                std::cin >> num_attendees;
            }
        }
        Info new_info(nickname, contact, city, num_attendees);
        audience_list.push_back(new_info);
        current_capacity += num_attendees;
    }
    std::cout << "截至目前，共有 " << current_capacity << " 人预约，预约信息如下：" << std::endl;
    for (const Info& info : audience_list) {
        info.display();
        std::cout << "----------------------------" << std::endl;
    }
    return 0;
}

 

7.实验任务7

#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 distance(const Date& date)const {
        return totalDays - date.totalDays;
    }
};
#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();
}
#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.distance(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;
        sum = 0;
    }
};
#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) {
    double interest = acc.getSum(date) * rate/date.distance(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();
}
#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;

}
#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; }
      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;
};