实验四

 1 #include "GradeCalc_2.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 }
23 //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？
24 //答：存储在GradeCalc对象内部的vector中。vector中的this指针访问成绩。通过调用std::vector<int>的push_back成员函数。
25 //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？
26 //答：求平均值；有，只保留整数部分；* 1.0是为了把int转化为float
27 //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？
28 //1.输入成绩时没有验证数据合法性
29 //2.代码中没有考虑极端情况，例如：
30 //用户创建 GradeCalc 对象时将学生人数 n 设置为 0，可能导致除零错误。
31 //vector<int> 容器为空时调用 min() 和 max() 函数会产生未定义行为。
32 //3.分数段设置的灵活性：分数段被硬编码为固定的 5 个区间，无法适应不同需求（如一些考试可能采用不同分数等级划分）
33 //4.数据封装：GradeCalc 类继承了 std::vector<int>，但 std::vector 是一种通用容器，不适合作为逻辑类的基类。容易破坏封装性，用户可以直接通过 GradeCalc 对象调用 vector 的方法修改数据，可能导致逻辑不一致。
34 //5.GradeCalc 类当前只支持整数成绩，但在某些场景（如 GPA 计算）可能需要支持浮点数。

task2

 1 #include<iostream>
 2 #include<vector>
 3 #include<string>
 4 
 5 
 6 using std::vector;
 7 using std::string;
 8 using std::cin;
 9 using std::cout;
10 using std::endl;
11 
12 #include "GradeCalc_3.hpp"
13 #include <iomanip>
14 
15 void test() {
16     int n;
17     cout << "输入班级人数: ";
18     cin >> n;
19 
20     GradeCalc c1("OOP", n);
21 
22     cout << "录入成绩: " << endl;;
23     c1.input();
24     cout << "输出成绩: " << endl;
25     c1.output();
26 
27     cout << string(20, '*') + "课程成绩信息" + string(20, '*') << endl;
28     c1.info();
29 }
30 
31 int main() {
32     test();
33 }
34 ////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。
35 //答：public的vector中；通过vector直接访问
36 //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？    
37 //答：类有多种设计：有时可直接将基类作为自定义类的数据元素，而使用类的公有继承则可以调用基类的接口，各有利弊

task3

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

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

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;
}

GradeCalc_2.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 }

GradeCalc_3.hpp

 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 }

task4_1.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 }

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         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 }
35 //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？
36 //答：cin.ignore(numeric_limits<streamsize>::max(), '\n');尤其用于处理输入流，直到下一个换行符（\n）之前，忽略（或“跳过”）输入缓冲区中的所有字符，最多忽略 numeric_limits<streamsize>::max() （一个极大的常量）个字符。
37 //清除/跳过缓存区剩下的\n
38 //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？
39 //答：in.ignore(numeric_limits<streamsize>::max(), '\n');直到下一个换行符（\n）之前，忽略输入流（cin）中的所有字符，忽略字符数量小于等于<>指定的最大值。
40 //处理输入后的残留字符，特别是在读取之前已经读取了其他数据时。

task4_3

 1 #pragma once
 2 #include<iostream>
 3 using namespace std;
 4 template <typename T>
 5 class GameResourceManager {
 6 private:
 7     T resouce;
 8 public:
 9     GameResourceManager(T Resource) :resouce(Resource) {}
10     T get()const {
11         return resouce;
12     }
13     void update(T value) {
14         resouce += value;
15         if (resouce < 0) resouce = 0;
16     }
17 };

grm.hpp

 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 }

task5.cpp

 1 #include<iostream>
 2 #include<string>
 3 
 4 using std::cout;
 5 class info {
 6 private:
 7     std::string nickname;
 8     std::string contact;
 9     std::string city;
10 
11     int n;
12  public:
13         info(const std::string & nick, const std::string & cont, const std::string & cit, int num): nickname(nick), contact(cont), city(cit), n(num){}
14     
15              void display()const {
16                  cout << "昵称: " << nickname << "\n";
17                  cout << "联系方式: " << contact << "\n";
18                  cout << "所在城市: " << city << "\n";
19                  cout<< "预定参加人数: " << n << "\n";
20         }
21     
22              int get_num() const {
23                  return n;
24         
25     }
26 };

info.hpp

 1 #include<iostream>
 2 #include"info.hpp"
 3 using namespace std;
 4 #include<iomanip>
 5 #include<vector>
 6 #include<limits>
 7 int main() {
 8     const int capacity = 100;
 9     cout << "录入用户信息：" << endl;
10     cout << left << setw(15) << "昵称" << left << setw(20) << "联系方式" << left << setw(15) << "所在城市" << left << setw(15) << "预定参加人数" << endl;
11     vector<info> audience_list;
12 
13     string nickname, city, contact;
14     int n;
15     int now_cap = 0;
16     while (true) {
17         if (!(cin >> nickname >> contact >> city >> n))
18             break;
19 
20         if (now_cap + n > capacity)
21         {
22             cout << "对不起，只剩80个位置。" << endl;
23             cout << "1.输入u，更新预约信息" << endl << "2.输入q，退出预定" << endl << "你的选择：" << endl;
24             string a;
25             cin >> a;
26             if (a == "u")
27             {
28                 cout << "请重新输入预约信息：" << endl;
29                 cin >> nickname >> contact >> city >> n;
30                 audience_list.push_back(info(nickname, contact, city, n));
31             }
32             else if (a == "q")
33                 break;
34         }
35         else {
36             now_cap += n;
37             audience_list.push_back(info(nickname, contact, city, n));
38         }
39     }
40     cout << "截至目前，一共有" << now_cap << "位听众预约。预约听众信息如下:" << endl;
41     for (info& i : audience_list)
42         i.display();
43 }

task6.cpp

 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 };
25 
26 #endif

data.h

 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 }

data.cpp

account.h

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

accumulator.h

 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 
33 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
34     record(date, amount, desc);
35     acc.change(date, getBalance());
36 }
37 
38 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
39     if (amount > getBalance()) {
40         error("not enough money");
41     }
42     else {
43         record(date, -amount, desc);
44         acc.change(date, getBalance());
45     }
46 }
47 
48 void SavingsAccount::settle(const Date& date) {
49     double interest = acc.getSum(date) * rate / date.distance(Date(date.getYear() - 1, 1, 1));
50     if (interest != 0) record(date, interest, "interest");
51     acc.reset(date, getBalance());
52 }
53 
54 CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee)
55     : Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) {
56 }
57 
58 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
59     record(date, amount, desc);
60     acc.change(date, getDebt());
61 }
62 
63 void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
64     if (amount - getBalance() > credit) {
65         error("not enough credit");
66     }
67     else {
68         record(date, -amount, desc);
69         acc.change(date, getDebt());
70     }
71 }
72 
73 void CreditAccount::settle(const Date& date) {
74     double interest = acc.getSum(date) * rate;
75     if (interest != 0) record(date, interest, "interest");
76     if (date.getMonth() == 1)
77         record(date, -fee, "annual fee");
78     acc.reset(date, getDebt());
79 }
80 
81 void CreditAccount::show() const {
82     Account::show();
83     cout << "\tAvailable credit:" << getAvailableCredit();
84 }

account.cpp

 1 #include"account.h"
 2 #include<iostream>
 3 
 4 using namespace std;
 5 
 6 int main() {
 7     Date date(2008, 11, 1);
 8     SavingsAccount sa1(date, "S3755217", 0.015);
 9     SavingsAccount sa2(date, "02342342", 0.015);
10     CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);
11 
12     sa1.deposit(Date(2008, 11, 5), 5000, "salary");
13     ca.withdraw(Date(2008, 11, 15), 2000, "buy a cell");
14     sa2.deposit(Date(2008, 11, 25), 10000, "sell stock 0323");
15 
16     ca.settle(Date(2008, 12, 1));
17 
18     ca.deposit(Date(2008, 12, 1), 2016, "repay the credit");
19     sa1.deposit(Date(2008, 12, 5), 5500, "salary");
20 
21     sa1.settle(Date(2009, 1, 1));
22     sa2.settle(Date(2009, 1, 1));
23     ca.settle(Date(2009, 1, 1));
24 
25     cout << endl;
26     sa1.show(); cout << endl;
27     sa2.show(); cout << endl;
28     ca.show(); cout << endl;
29     cout << "Total:" << Account::getTotal() << endl;
30 
31     return 0;
32 }

task7

posted @ 2024-11-23 19:58 十二门阅读(8) 评论(0) 编辑收藏举报

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