实验四

实验2

GradeCalc.hpp:

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <string>
#include <vector>

using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;

class GradeCalc : public vector<int>
{
public:
    GradeCalc(const string &cname, int size);
    void input();                      // 录入成绩
    void output() const;               // 输出成绩
    void sort(bool ascending = false); // 排序 (默认降序)
    int min() const;                   // 返回最低分
    int max() const;                   // 返回最高分
    float average() const;             // 返回平均分
    void info();                       // 输出课程成绩信息

private:
    void compute(); // 成绩统计

private:
    string course_name;                          // 课程名
    int n;                                       // 课程人数
    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]
    vector<double> rates = vector<double>(5, 0); // 保存各分数段比例
};

GradeCalc::GradeCalc(const string &cname, int size) : course_name{cname}, n{size} {}

void GradeCalc::input()
{
    int grade;

    for (int i = 0; i < n; ++i)
    {
        cin >> grade;
        this->push_back(grade);
    }
}

void GradeCalc::output() const
{
    for (auto ptr = this->begin(); ptr != this->end(); ++ptr)
        cout << *ptr << " ";
    cout << endl;
}

void GradeCalc::sort(bool ascending)
{
    if (ascending)
        std::sort(this->begin(), this->end());
    else
        std::sort(this->begin(), this->end(), std::greater<int>());
}

int GradeCalc::min() const
{
    return *std::min_element(this->begin(), this->end());
}

int GradeCalc::max() const
{
    return *std::max_element(this->begin(), this->end());
}

float GradeCalc::average() const
{
    return std::accumulate(this->begin(), this->end(), 0) * 1.0 / n;
}

void GradeCalc::compute()
{
    for (int grade : *this)
    {
        if (grade < 60)
            counts.at(0)++;
        else if (grade >= 60 && grade < 70)
            counts.at(1)++;
        else if (grade >= 70 && grade < 80)
            counts.at(2)++;
        else if (grade >= 80 && grade < 90)
            counts.at(3)++;
        else if (grade >= 90)
            counts.at(4)++;
    }

    for (int i = 0; i < rates.size(); ++i)
        rates.at(i) = counts.at(i) * 1.0 / n;
}

void GradeCalc::info()
{
    cout << "课程名称:\t" << course_name << endl;
    cout << "排序后成绩: \t";
    sort();
    output();
    cout << "最高分:\t" << max() << endl;
    cout << "最低分:\t" << min() << endl;
    cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;

    compute(); // 统计各分数段人数、比例

    vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)", "[80, 90)", "[90, 100]"};
    for (int i = tmp.size() - 1; i >= 0; --i)
        cout << tmp[i] << "\t: " << counts[i] << "人\t"
             << std::fixed << std::setprecision(2) << rates[i] * 100 << "%" << endl;
}

task2.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();
}

 

问题1：派生类GradeCalc定义中，成绩存储在哪里？派生类方法sort, min, max, average,
output都要访问成绩，是通过什么接口访问到每个成绩的？input方法是通过什么接口实现数
据存入对象的？
1.在GradeCalc派生类中，成绩储存在继承的vector<int>中。
2.sort通过sort函数；min通过min_element函数；max通过max_element函数；average通过accumulate函数；output通过迭代器。
3.input是通过push_back实现的。
问题2：代码line68分母的功能是？去掉乘以1.0代码，重新编译、运行，结果有影响吗？为什
么要乘以1.0？
1.分母是n除以n是计算平均值的。
2.有影响，计算平均值时候要转化为double类型。
3.否则int类型会让数据不准，小数部分没法计算，被舍弃了。
问题3：从真实应用场景角度考虑，GradeCalc类在设计及代码实现细节上，有哪些地方尚未
考虑周全，仍需继续迭代、完善？
1.cin输入时候没有对成绩的范围进行认定。
2.处理成绩时，没有保证成绩的私密性。

实验3

GradeCalc.hpp

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <string>
#include <vector>

using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;

class GradeCalc
{
public:
    GradeCalc(const string &cname, int size);
    void input();                      // 录入成绩
    void output() const;               // 输出成绩
    void sort(bool ascending = false); // 排序 (默认降序)
    int min() const;                   // 返回最低分
    int max() const;                   // 返回最高分
    float average() const;             // 返回平均分
    void info();                       // 输出课程成绩信息

private:
    void compute(); // 成绩统计

private:
    string course_name;                          // 课程名
    int n;                                       // 课程人数
    vector<int> grades;                          // 课程成绩
    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]
    vector<double> rates = vector<double>(5, 0); // 保存各分数段比例
};

GradeCalc::GradeCalc(const string &cname, int size) : course_name{cname}, n{size} {}

void GradeCalc::input()
{
    int grade;

    for (int i = 0; i < n; ++i)
    {
        cin >> grade;
        grades.push_back(grade);
    }
}

void GradeCalc::output() const
{
    for (int grade : grades)
        cout << grade << " ";
    cout << endl;
}

void GradeCalc::sort(bool ascending)
{
    if (ascending)
        std::sort(grades.begin(), grades.end());
    else
        std::sort(grades.begin(), grades.end(), std::greater<int>());
}

int GradeCalc::min() const
{
    return *std::min_element(grades.begin(), grades.end());
}

int GradeCalc::max() const
{
    return *std::max_element(grades.begin(), grades.end());
}

float GradeCalc::average() const
{
    return std::accumulate(grades.begin(), grades.end(), 0) * 1.0 / n;
}

void GradeCalc::compute()
{
    for (int grade : grades)
    {
        if (grade < 60)
            counts.at(0)++;
        else if (grade >= 60 && grade < 70)
            counts.at(1)++;
        else if (grade >= 70 && grade < 80)
            counts.at(2)++;
        else if (grade >= 80 && grade < 90)
            counts.at(3)++;
        else if (grade >= 90)
            counts.at(4)++;
    }

    for (int i = 0; i < rates.size(); ++i)
        rates.at(i) = counts.at(i) * 1.0 / n;
}

void GradeCalc::info()
{
    cout << "课程名称:\t" << course_name << endl;
    cout << "排序后成绩: \t";
    sort();
    output();
    cout << "最高分:\t" << max() << endl;
    cout << "最低分:\t" << min() << endl;
    cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;

    compute(); // 统计各分数段人数、比例

    vector<string> tmp{"[0, 60)  ", "[60, 70)", "[70, 80)", "[80, 90)", "[90, 100]"};
    for (int i = tmp.size() - 1; i >= 0; --i)
        cout << tmp[i] << "\t: " << counts[i] << "人\t"
             << std::fixed << std::setprecision(2) << rates[i] * 100 << "%" << endl;
}

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();
}

 

问题1：组合类GradeCalc定义中，成绩存储在哪里？组合类方法sort, min, max, average,
output都要访问成绩，是通过什么接口访问到每个成绩的？观察与实验任务2在代码写法细节
上的差别。
1.存储在类型为vector<int>的私有成员grades里。
2.min通过min_element函数；max通过max_element函数；average通过accumulate函数；output通过遍历每个元素打印出来。
问题2：对比实验任务2和实验任务3，主体代码逻辑（测试代码）没有变更，类GradeCalc的
接口也没变，变化的是类GradeCalc的设计及接口内部实现细节。你对面向对象编程有什么新
的理解和领悟吗？
1.通过多文件类编写程序，可以随时的更改函数的实现的设计。而接口什么的都没有改变。

实验4

task4_1.cpp

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

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;

    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：去掉task4_1.cpp的line35，重新编译、运行，给出此时运行结果截图。查阅资料，回答
line35在这里的用途是什么？
这句话是在清楚我cin留下的换行符\n，避免影响到getline函数。

task4_2.cpp

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

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();
}

 

 

task4_3.cpp

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

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：去掉task4_3.cpp的line16，重新编译、运行，给出此时运行结果。查阅资料，回答line16
在这里的用途是什么？
这行代码的清除了我输入n留下的换行符，如果不清除就会getline一个空的字符串。

实验五

grm.hpp

#include <iostream>
using namespace std;
template <typename T>
class GameResourceManager
{
public:
    GameResourceManager(T resource);
    T get();
    void update(T value);

private:
    T resource;
};
template <typename T>
GameResourceManager<T>::GameResourceManager(T resource) : resource{resource} {}
template <typename T>

T GameResourceManager<T>::get()
{
    return resource;
}
template <typename T>

void GameResourceManager<T>::update(T value)
{
    resource += value;
    if (resource < 0)
        resource = 0;
}

task5.cpp

#include "grm.hpp"
#include <iostream>

using std::cout;
using std::endl;

void test1()
{
    GameResourceManager<float> HP_manager(99.99);
    cout << "当前生命值: " << HP_manager.get() << endl;
    HP_manager.update(9.99);
    cout << "增加9.99生命值后, 当前生命值: " << HP_manager.get() << endl;
    HP_manager.update(-999.99);
    cout << "减少999.99生命值后, 当前生命值: " << HP_manager.get() << endl;
}

void test2()
{
    GameResourceManager<int> Gold_manager(100);
    cout << "当前金币数量: " << Gold_manager.get() << endl;
    Gold_manager.update(50);
    cout << "增加50个金币后, 当前金币数量: " << Gold_manager.get() << endl;
    Gold_manager.update(-99);
    cout << "减少99个金币后, 当前金币数量: " << Gold_manager.get() << endl;
}

int main()
{
    cout << "测试1: 用float类型对类模板GameResourceManager实例化" << endl;
    test1();
    cout << endl;

    cout << "测试2: 用int类型对类模板GameResourceManager实例化" << endl;
    test2();
}

实验6

info.hpp

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

class Info
{
public:
    string nickname;
    string contact;
    string city;
    int n;
    Info(string nickname, string contact, string city, int n) : nickname{nickname}, contact{contact}, city{city}, n{n} {}
    void dispaly()
    {
        cout << "------------------------------------------------------------\n";
        cout << "昵称：       " << nickname << endl;
        cout << "联系方式     " << contact << endl;
        cout << "所在城市     " << city << endl;
        cout << "预定人数     " << n << endl;
        cout << "-------------------------------------------------------------\n";
    }
};

task6.cpp

#include "Info.hpp"
#include <iostream>
#include <limits>
#include <string>
#include <vector>

using namespace std;

int main()
{
    const int capacity = 100;
    vector<Info> audience_lst;
    int total = 0, n;
    string nickname, city, contact;
    cout << "昵称           " << "联系方式（邮箱/手机号）       " << "城市      " << "人数" << endl;

    while (cin >> nickname >> contact >> city >> n)
    {
        if (total + n <= capacity)
        {
            total += n;
            audience_lst.emplace_back(nickname, contact, city, n);
        }
        else
        {
            cout << "对不起，只剩下" << capacity - total << "个位置" << endl;
            cout << "输入u，更新预定信息" << endl;
            cout << "输入q，放弃预定" << endl;
            char choice;
            cin >> choice;
            if (choice == 'u')
            {
                cout << "请重新输入信息：" << endl;
                continue;
            }
            else
                break;
        }
    }
    cout << "截至目前一共有" << total << "位听众预约" << endl;
    for (Info &info : audience_lst)
        info.dispaly();
    return 0;
}

实验7

date.h

#ifndef __DATE_H__
#define __DATE_H__

class Date
{
private:
    int year;      // 年
    int month;     // 月
    int day;       // 日
    int totalDays; // 该日期是从公元元年1月1日开始的第几天
public:
    Date(int year, int month, int day); // 用年、月、日构造日期
    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;
    // 计算两个日期之间相差多少天
    int distance(const Date &date) const
    {
        return totalDays - date.totalDays;
    }
};
#endif

date.cpp

#include "date.h"
#include <cstdlib>
#include <iostream>
using namespace std;

// 命名空间使下面的定义只在当前文件中有效
namespace
{
    // 存储平年中的某个月1日之前有多少天，为便于getMaxDay函数的实现，该数组多出一项
    const int DAYS_BEFORE_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_BEFORE_MONTH[month - 1] + day;
    if (isLeapYear() && month > 2)
        totalDays++;
}

int Date::getMaxDay() const
{
    if (isLeapYear() && month == 2)
    {
        return 29;
    }
    else
    {
        return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
    }
}

void Date::show() const
{
    cout << getYear() << '-' << getMonth() << '-' << getDay();
}

accumulator.h

#ifndef _ACCUMULATOR_H_
#define _ACCUMULATOR_H_
#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 = value;
        sum = 0;
    }
};
#endif

account.h

#ifndef _ACCOUNT_H_
#define _ACCOUNT_H_
#include "accumulator.h"
#include "date.h"
#include <string>
class Account
{
private:
    std::string id;
    double balance;
    static double total;

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

public:
    const std::string &getId() const { 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 std::string &id, double rate);
    double getRate() const { return rate; }
    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
    {
        double balance = getBalance();
        return (balance < 0 ? balance : 0);
    }

public:
    CreditAccount(const Date &date, const std::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 { return credit; }
    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;
};
#endif

account.cpp

#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double Account::total = 0;

// Account类的实现
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类相关成员函数的实现
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类相关成员函数的实现
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());
}

7_10.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;
}