1 .hpp
2 #pragma once
3 #include<iostream>
4 #include<vector>
5 #include<string>
6 #include<algorithm>
7 #include<numeric>
8 #include<iomanip>
9 using namespace std;
10 class GradeCalc :public vector<int> {
11 public:
12 GradeCalc(const string& cname, int size);
13 void input();
14 void output()const;
15 void sort(bool ascending = false);
16 int min()const;
17 int max()const;
18 float average()const;
19 void info();
20 private:
21 void compute();
22 private:
23 string course_name;
24 int n;
25 vector<int> counts = vector<int>(5, 0);
26 vector<double> rates = vector<double>(5, 0);
27 };
28 GradeCalc::GradeCalc(const string& cname, int size) :course_name{ cname }, n{ size } {}
29 void GradeCalc::input() {
30 int grade;
31 for (int i = 0; i < n; i++) {
32 cin >> grade;
33 this->push_back(grade);
34 }
35 }
36 void GradeCalc::output()const {
37 for (auto ptr = this->begin(); ptr != this->end(); ptr++) {
38 cout << *ptr << " ";
39 }
40 cout << endl;
41 }
42 void GradeCalc::sort(bool ascending) {
43 if (ascending) std::sort(this->begin(), this->end());
44 else std::sort(this->begin(), this->end(), greater<int>());
45 }
46 int GradeCalc::min()const {
47 return *min_element(this->begin(), this->end());
48 }
49 int GradeCalc::max()const {
50 return *max_element(this->begin(), this->end());
51 }
52 float GradeCalc::average()const {
53 return accumulate(this->begin(), this->end(), 0) * 1.0 / n;
54 }
55 void GradeCalc::compute() {
56 for (int grade : *this) {
57 if (grade < 60) counts.at(0)++;
58 else if (grade >= 60 && grade < 70) counts.at(1)++;
59 else if (grade >= 70 && grade < 80) counts.at(2)++;
60 else if (grade >= 80 && grade < 90) counts.at(3)++;
61 else if (grade >= 90)counts.at(4)++;
62
63 }
64 for (int i = 0; i < rates.size(); i++) {
65 rates.at(i) = counts.at(i) * 1.0 / n;
66 }
67 }
68 void GradeCalc::info() {
69 cout << "课程名称:\t" << course_name << endl;
70 cout << "排序后课程成绩: \t";
71 sort(); output();
72 cout << "最高分:\t" << max() << endl;
73 cout << "最低分:\t" << min() << endl;
74 cout << "平均分:\t" << fixed << setprecision(2) << average() << endl;
75 compute();
76 vector<string> tmp{ "[0,60) ","[60,70)","[70,80)","[80,90)","[90,100]" };
77 for (int i = tmp.size() - 1; i >= 0; i--)
78 cout << tmp[i] << "\t: " << counts[i] << "人\t" << fixed << setprecision(2) << rates[i] * 100 << "%" << endl;
79 }
80
81
82 .cpp
83 #include "GradeCalc.hpp"
84 #include<iomanip>
85 void test() {
86 int n;
87 cout << "请输入班级人数: ";
88 cin >> n;
89 GradeCalc c1("OPP", n);
90 cout << "录入成绩: " << endl;
91 c1.input();
92 cout << "输出成绩: " << endl;
93 c1.output();
94 cout << string(20, '*') + "课程成绩信息" + string(20, '*') << endl;
95 c1.info();
96 }
97 int main() {
98 test();
99 }
task 2
task2
问题1:储存在它继承的基类vector中通过public继承方式继承的基类中的protected接口访问每一个成绩，和实现数据存入.
问题2:计算this所指向容器所有元素的和并取平均。会。整形数据整除会导致数据小数部分的丢失，乘以1.0将分母转化成浮点型数据。
问题3：缺乏对输入数据合法性的判断，如果输入的数据中存在不合法的数据，会导致程序运行结果出错。
1 .hpp
2 #pragma once
3 #include <iostream>
4 #include <vector>
5 #include <string>
6 #include <algorithm>
7 #include <numeric>
8 #include <iomanip>
9
10 using std::vector;
11 using std::string;
12 using std::cin;
13 using std::cout;
14 using std::endl;
15
16 class GradeCalc {
17 public:
18 GradeCalc(const string& cname, int size);
19 void input(); // 录入成绩
20 void output() const; // 输出成绩
21 void sort(bool ascending = false); // 排序 (默认降序)
22 int min() const; // 返回最低分
23 int max() const; // 返回最高分
24 float average() const; // 返回平均分
25 void info(); // 输出课程成绩信息
26
27 private:
28 void compute(); // 成绩统计
29
30 private:
31 string course_name; // 课程名
32 int n; // 课程人数
33 vector<int> grades; // 课程成绩
34 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]
35 vector<double> rates = vector<double>(5, 0); // 保存各分数段比例
36 };
37
38 GradeCalc::GradeCalc(const string& cname, int size) : course_name{ cname }, n{ size } {}
39
40 void GradeCalc::input() {
41 int grade;
42
43 for (int i = 0; i < n; ++i) {
44 cin >> grade;
45 grades.push_back(grade);
46 }
47 }
48
49 void GradeCalc::output() const {
50 for (int grade : grades)
51 cout << grade << " ";
52 cout << endl;
53 }
54
55 void GradeCalc::sort(bool ascending) {
56 if (ascending)
57 std::sort(grades.begin(), grades.end());
58 else
59 std::sort(grades.begin(), grades.end(), std::greater<int>());
60
61 }
62
63 int GradeCalc::min() const {
64 return *std::min_element(grades.begin(), grades.end());
65 }
66
67 int GradeCalc::max() const {
68 return *std::max_element(grades.begin(), grades.end());
69 }
70
71 float GradeCalc::average() const {
72 return std::accumulate(grades.begin(), grades.end(), 0) * 1.0 / n;
73 }
74
75 void GradeCalc::compute() {
76 for (int grade : grades) {
77 if (grade < 60)
78 counts.at(0)++;
79 else if (grade >= 60 && grade < 70)
80 counts.at(1)++;
81 else if (grade >= 70 && grade < 80)
82 counts.at(2)++;
83 else if (grade >= 80 && grade < 90)
84 counts.at(3)++;
85 else if (grade >= 90)
86 counts.at(4)++;
87 }
88
89 for (int i = 0; i < rates.size(); ++i)
90 rates.at(i) = counts.at(i) * 1.0 / n;
91 }
92
93 void GradeCalc::info() {
94 cout << "课程名称:\t" << course_name << endl;
95 cout << "排序后成绩: \t";
96 sort(); output();
97 cout << "最高分:\t" << max() << endl;
98 cout << "最低分:\t" << min() << endl;
99 cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
100
101 compute(); // 统计各分数段人数、比例
102
103 vector<string> tmp{ "[0, 60) ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]" };
104 for (int i = tmp.size() - 1; i >= 0; --i)
105 cout << tmp[i] << "\t: " << counts[i] << "人\t"
106 << std::fixed << std::setprecision(2) << rates[i] * 100 << "%" << endl;
107 }
108
109
110 .cpp
111 #include "GradeCalc.hpp"
112 #include <iomanip>
113
114 void test() {
115 int n;
116 cout << "输入班级人数: ";
117 cin >> n;
118
119 GradeCalc c1("OOP", n);
120
121 cout << "录入成绩: " << endl;;
122 c1.input();
123 cout << "输出成绩: " << endl;
124 c1.output();
125
126 cout << string(20, '*') + "课程成绩信息" + string(20, '*') << endl;
127 c1.info();
128 }
129
130 int main() {
131 test();
132 }
task 2
task3
问题1：储存在类中的私有数据成员vector<int> grades中。直接访问类中的私有成员grades。
问题2：在某些情况下可以不用继承基类，而直接将基类作为自定义类的数据元素。
1 1.
2 #include<iostream>
3 #include<string>
4 #include<limits>
5 using namespace std;
6 void test1() {
7 string s1, s2;
8 cin >> s1 >> s2;
9 cout << "s1: " << s1 << endl;
10 cout << "s2: " << s2 << endl;
11 }
12 void test2() {
13 string s1, s2;
14 getline(cin, s1);
15 getline(cin, s2);
16 cout << "s1: " << s1 << endl;
17 cout << "s2: " << s2 << endl;
18 }
19 void test3() {
20 string s1, s2;
21 getline(cin, s1, ' ');
22 getline(cin, s2);
23 cout << "s1: " << s1 << endl;
24 cout << "s2: " << s2 << endl;
25 }
26 int main() {
27 cout << "测试1: 使用标准输入流对象cin输入字符串" << endl;
28 test1();
29 cout << endl;
30 cin.ignore(numeric_limits<streamsize>::max(), '\n');
31 cout << "测试2: 使用函数getline()输入字符串" << endl;
32 test2();
33 cout << endl;
34 cout << "测试3: 使用函数getline()输入字符串, 指定字符串分隔符" << endl;
35 test3();
36
37 }
38
39 2.
40 #include<iostream>
41 #include<string>
42 #include<vector>
43 #include<limits>
44 using namespace std;
45 void output(const vector<string>& v) {
46 for (auto& s : v)
47 cout << s << endl;
48 }
49 void test() {
50 int n;
51 while (cout << "Enter n: ", cin >> n) {
52 vector<string> v1;
53 for (int i = 0; i < n; i++) {
54 string s;
55 cin >> s;
56 v1.push_back(s);
57 }
58 cout << "output v1: " << endl;
59 output(v1);
60 cout << endl;
61 }
62
63 }
64 int main() {
65 cout << "测试: 使用cin多组输入字符串" << endl;
66 test();
67 }
68
69
70 3.
71 #include<iostream>
72 #include<string>
73 #include<vector>
74 #include<climits>
75 using namespace std;
76 void output(const vector<string>& v) {
77 for (auto& s : v)
78 cout << s << endl;
79 }
80 void test() {
81 int n;
82 while (cout << "Enter n: ", cin >> n) {
83 vector<string> v2;
84 for (int i = 0; i < n; i++) {
85 string s;
86 getline(cin, s);
87 v2.push_back(s);
88 }
89 cout << "output v2: " << endl;
90 output(v2);
91 cout << endl;
92 }
93 }
94 int main() {
95 cout << "测试: 使用函数getline()多组输入字符串" << endl;
96 test();
97 return 0;
98 }
task 4
task4 在读取整数（或其他数据类型）时，cin 会读取输入，但它不会清除缓冲区中的换行符（即用户按下回车键时生成的 '\n'）。如果你随后使用 getline() 来读取字符串，getline() 会立即遇到这个换行符并认为输入已经结束。因此，我们使用 cin.ignore() 来跳过这个换行符，确保后续的 getline() 能正确读取用户的字符串输入。
1 hpp
2 #pragma once
3 #include<iostream>
4 using namespace std;
5 template<typename T>
6 class GameResourceManager {
7 private:
8 T resouce;
9 public:
10 GameResourceManager(T Resource):resouce(Resource){}
11 T get()const {
12 return resouce;
13 }
14 void update(T num) {
15 resouce += num;
16 if (resouce < 0) resouce = 0;
17 }
18
19 };
20
21
22
23 cpp
24 #include "grm.hpp"
25 #include <iostream>
26
27 using std::cout;
28 using std::endl;
29
30 void test1() {
31 GameResourceManager<float> HP_manager(99.99);
32 cout << "当前生命值: " << HP_manager.get() << endl;
33 HP_manager.update(9.99);
34 cout << "增加9.99生命值后, 当前生命值: " << HP_manager.get() << endl;
35 HP_manager.update(-999.99);
36 cout << "减少999.99生命值后, 当前生命值: " << HP_manager.get() << endl;
37 }
38
39 void test2() {
40 GameResourceManager<int> Gold_manager(100);
41 cout << "当前金币数量: " << Gold_manager.get() << endl;
42 Gold_manager.update(50);
43 cout << "增加50个金币后, 当前金币数量: " << Gold_manager.get() << endl;
44 Gold_manager.update(-99);
45 cout << "减少99个金币后, 当前金币数量: " << Gold_manager.get() << endl;
46 }
47
48
49 int main() {
50 cout << "测试1: 用float类型对类模板GameResourceManager实例化" << endl;
51 test1();
52 cout << endl;
53
54 cout << "测试2: 用int类型对类模板GameResourceManager实例化" << endl;
55 test2();
56 }
task 5
1 .hpp
2 #pragma once
3 #include<iostream>
4 #include<iomanip>
5 using namespace std;
6 class Info {
7 public:
8 string nickname;
9 string contact;
10 string city;
11 int n;
12 public:
13 Info(string nickname_,string contact_,string city_,int n_):nickname(nickname_),contact(contact_),city(city_), n(n_) {}
14 void display()const {
15 cout << string(40, '*') << endl;
16 cout << "昵称:" << "\t" << nickname << endl;
17 cout << "联系方式:" << "\t" << contact << endl;
18 cout << "所在城市:" << "\t" << city << endl;
19 cout << "预定人数:" << "\t" << n << endl;
20 }
21 };
22
23
24 .cpp
25 #include"Info.h"
26 #include<iomanip>
27 #include<vector>
28 const int capacity = 100;
29 int main() {
30 cout << "录入用户预约信息:" << endl;
31 cout << "录入用户数:";
32 int n;
33 cin >> n;
34 cout << "昵称" << "\t" << "联系方式(邮箱/手机号)" << "\t" << "所在城市" << "\t" << "预定参加人数" << endl;
35 vector<Info> v;
36 string nickname;
37 string contact;
38 string city;
39 int num;
40 int sum = 0;
41 for (int i = 0; i < n; i++) {
42 cin >> nickname >> contact >> city >> num;
43 sum += num;
44 if (sum > capacity) {
45 char choice;
46 cout << "对不起，只剩" << 100 + num - sum << "个位置" << endl;
47 cout << "1. 输入u,更新(update)预定信息" << endl;
48 cout << "2. 输入q,退出预定" << endl;
49 cout << "你的选择: ";
50 cin >> choice;
51 if (choice == 'u') {
52 sum -= num;
53 cout << "请重新输入预定信息" << endl;
54 cin >> nickname >> contact >> city >> num;
55 sum += num;
56 }
57 else if(choice=='q') {
58 continue;
59 }
60 }
61 v.push_back(Info(nickname, contact, city, num));
62 }
63 cout << "截至目前,一共有" << sum << "位听众预约。" << "预约听众信息如下:" << endl;
64 for (auto i : v) {
65 i.display();
66 }
67 cout << string(40, '*');
68 return 0;
69 }
task 6
1 date.h
2 #pragma once
3 class Date {
4 private:
5 int year;
6 int month;
7 int day;
8 int totalDays;
9 public:
10 Date(int year, int month, int day);
11 int getYear()const { return year; }
12 int getMonth()const { return month; }
13 int getDay()const { return day; }
14 int getMaxDay()const;
15 bool isLeapYear()const {
16 return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
17 }
18 void show() const;
19 int distance(const Date& date)const {
20 return totalDays - date.totalDays;
21 }
22 };
23 accumulator.h
24 #pragma once
25 #include "date.h"
26 class Accumulator {
27 private:
28 Date lastDate;
29 double value;
30 double sum;
31 public:
32 Accumulator(const Date&date,double value):lastDate(date),value(value),sum{0}{}
33 double getSum(const Date& date) const {
34 return sum + value * date.distance(lastDate);
35 }
36 void change(const Date& date, double value) {
37 sum = getSum(date);
38 lastDate = date;
39 this->value = value;
40 }
41 void reset(const Date& date, double value) {
42 lastDate = date;
43 this->value;
44 sum = 0;
45 }
46 };
47 account.h
48 #pragma once
49 #include"date.h"
50 #include"accumulator.h"
51 #include<string>
52 using namespace std;
53 class Account {
54 private:
55 string id;
56 double balance;
57 static double total;
58 protected:
59 Account(const Date& date, const string &id);
60 void record(const Date& date, double amount, const string& desc);
61 void error(const string& msg) const;
62 public:const string& getId() { return id; }
63 double getBalance()const { return balance; }
64 static double getTotal() { return total; }
65 void show()const;
66 };
67 class SavingsAccount:public Account {
68 private:
69 Accumulator acc;
70 double rate;
71 public:
72 SavingsAccount(const Date& date, const string& id, double rate);
73 double getRate() const { return rate; }
74 void deposit(const Date& date, double amount, const string& desc);
75 void withdraw(const Date& date, double amount, const string& desc);
76 void settle(const Date& date);
77 };
78 class CreditAccount :public Account {
79 private:
80 Accumulator acc;
81 double credit;
82 double rate;
83 double fee;
84 double getDebt()const {
85 double balance = getBalance();
86 return(balance < 0 ? balance : 0);
87 }
88 public:CreditAccount(const Date& date, const string& id, double credit, double rate, double fee);
89 double getCredit()const { return credit; }
90 double getRate()const { return rate; }
91 double getFee() const { return fee; }
92 double getAvailableCredit()const {
93 if (getBalance() < 0)return credit + getBalance();
94 else return credit;
95 }
96 void deposit(const Date& date, double amount, const string& desc);
97 void withdraw(const Date& date, double amount, const string& desc);
98 void settle(const Date& date);
99 void show()const;
100 };
101
102 date.cpp
103 #include"date.h"
104 #include<iostream>
105 #include<cstdlib>
106 using namespace std;
107 namespace {
108 const int DAYS_BEFIRE_MONTH[] = { 0,31,59,90,120,151,181,212,243,273,304 ,334,365 };
109 }
110 Date::Date(int year, int month, int day) :year(year), month(month), day(day) {
111 if (day <= 0 || day > getMaxDay()) {
112 cout << "Invalid date: ";
113 show();
114 cout << endl;
115 exit(1);
116 }
117 int years = year - 1;
118 totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFIRE_MONTH[month - 1] + day;
119 if (isLeapYear() && month > 2) totalDays++;
120 }
121 int Date::getMaxDay()const {
122 if (isLeapYear() && month == 2)
123 return 29;
124 else return DAYS_BEFIRE_MONTH[month] - DAYS_BEFIRE_MONTH[month - 1];
125 }
126 void Date::show()const {
127 cout << getYear() << "-" << getMonth() << "-" << getDay();
128 }
129
130 accumulator.cpp
131 #include "account.h"
132 #include <cmath>
133 #include<iostream>
134 using namespace std;
135 double Account::total = 0;
136 Account::Account(const Date& date, const string& id) :id(id), balance(0) {
137 date.show();
138 cout << "\t#" << id << "created" << endl;
139 }
140 void Account::record(const Date& date, double amount, const string& desc) {
141 amount = floor(amount * 100 + 0.5) / 100;
142 balance += amount;
143 total += amount;
144 date.show();
145 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
146 }
147 void Account::show()const { cout << id << "\tBalance:" << balance; }
148 void Account::error(const string& msg)const {
149 cout << "Error(#" << id << "):" << msg << endl;
150 }
151 SavingsAccount::SavingsAccount(const Date&date,const string &id,double rate):Account(date,id),rate(rate),acc(date,0){}
152 void SavingsAccount::deposit(const Date& date, double amount, const string& desc) {
153 record(date, amount, desc);
154 acc.change(date, getBalance());
155 }
156 void SavingsAccount::withdraw(const Date& date, double amount, const string& desc) {
157 if (amount > getBalance()) {
158 error("not enough money");
159 }
160 else {
161 record(date, -amount, desc);
162 acc.change(date, getBalance());
163 }
164 }
165 void SavingsAccount::settle(const Date& date) {
166 double interest = acc.getSum(date) * rate/date.distance(Date(date.getYear()-1,1,1));
167 if (interest != 0)record(date, interest, "interest");
168 acc.reset(date, getBalance());
169 }
170 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){}
171 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
172 record(date, amount, desc);
173 acc.change(date, getDebt());
174 }
175 void CreditAccount::withdraw(const Date& date, double amount, const string& desc) {
176 if (amount - getBalance() > credit) {
177 error("not enouogh credit");
178 }
179 else {
180 record(date, -amount, desc);
181 acc.change(date, getDebt());
182 }
183 }
184 void CreditAccount::settle(const Date& date) {
185 double interest = acc.getSum(date) * rate;
186 if (interest != 0) record(date, interest, "interest");
187 if (date.getMonth() == 1)record(date, -fee, "annual fee");
188 acc.reset(date, getDebt());
189 }
190 void CreditAccount::show()const {
191 Account::show();
192 cout << "\tAvailable credit:" << getAvailableCredit();
193 }
194 task7.cpp
195 #include "account.h"
196 #include<iostream>
197 using namespace std;
198 int main() {
199 Date date(2008, 11, 1);
200 SavingsAccount sa1(date, "S3755217", 0.015);
201 SavingsAccount sa2(date, "02342342", 0.015);
202 CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);
203 sa1.deposit(Date(2008, 11, 5), 5000, "Salary");
204 ca.withdraw(Date(2008, 11, 15), 2000, "buy a cell");
205 sa2.deposit(Date(2008, 11, 25), 10000, "sell stock 0323");
206 ca.settle(Date(2008, 12, 1));
207 ca.deposit(Date(2008, 12,1), 2016, "repay the credit");
208 sa1.deposit(Date(2008, 12, 5), 5500, "salary");
209 sa1.settle(Date(2009, 1, 1));
210 sa2.settle(Date(2009, 1, 1));
211 ca.settle(Date(2009, 1, 1));
212 cout << endl;
213 sa1.show(); cout << endl;
214 sa2.show(); cout << endl;
215 ca.show(); cout << endl;
216 cout << "Total: " << Account::getTotal() << endl;
217 return 0;
218
219 }
task 7
task7
1.定义一个基类，account,并从基类继承得到了两个派生类SavingAccounts和CreditAccounts.
2.抽象出了一个新的类accumulator专门用于计算银行账户存款的积累.
不足:虽然派生类中有相同的成员函数，deposit,withdraw,settle,但是由于实现不同只能在各自派生类中定义。