Task2：
1 Gradecalc.cpp:
2 #include <iostream>
3 #include <vector>
4 #include <string>
5 #include <algorithm>
6 #include <numeric>
7 #include <iomanip>
8
9 using std::vector;
10 using std::string;
11 using std::cin;
12 using std::cout;
13 using std::endl;
14
15 class GradeCalc: public vector<int> {
16 public:
17 GradeCalc(const string &cname, int size);
18 void input(); // 录入成绩
19 void output() const; // 输出成绩
20 void sort(bool ascending = false); // 排序 (默认降序)
21 int min() const; // 返回最低分
22 int max() const; // 返回最高分
23 float average() const; // 返回平均分
24 void info(); // 输出课程成绩信息
25
26 private:
27 void compute(); // 成绩统计
28
29 private:
30 string course_name; // 课程名
31 int n; // 课程人数
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 this->push_back(grade);
44 }
45 }
46
47 void GradeCalc::output() const {
48 for(auto ptr = this->begin(); ptr != this->end(); ++ptr)
49 cout << *ptr << " ";
50 cout << endl;
51 }
52
53 void GradeCalc::sort(bool ascending) {
54 if(ascending)
55 std::sort(this->begin(), this->end());
56 else
57 std::sort(this->begin(), this->end(), std::greater<int>());
58 }
59
60 int GradeCalc::min() const {
61 return *std::min_element(this->begin(), this->end());
62 }
63
64 int GradeCalc::max() const {
65 return *std::max_element(this->begin(), this->end());
66 }
67
68 float GradeCalc::average() const {
69 return std::accumulate(this->begin(), this->end(), 0) * 1.0 / n;
70 }
71
72 void GradeCalc::compute() {
73 for(int grade: *this) {
74 if(grade < 60)
75 counts.at(0)++;
76 else if(grade >= 60 && grade < 70)
77 counts.at(1)++;
78 else if(grade >= 70 && grade < 80)
79 counts.at(2)++;
80 else if(grade >= 80 && grade < 90)
81 counts.at(3)++;
82 else if(grade >= 90)
83 counts.at(4)++;
84 }
85
86 for(int i = 0; i < rates.size(); ++i)
87 rates.at(i) = counts.at(i) * 1.0 / n;
88 }
89
90 void GradeCalc::info() {
91 cout << "课程名称:\t" << course_name << endl;
92 cout << "排序后成绩: \t";
93 sort(); output();
94 cout << "最高分:\t" << max() << endl;
95 cout << "最低分:\t" << min() << endl;
96 cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
97
98 compute(); // 统计各分数段人数、比例
99
100 vector<string> tmp{"[0, 60) ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
101 for(int i = tmp.size()-1; i >= 0; --i)
102 cout << tmp[i] << "\t: " << counts[i] << "人\t"
103 << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl;
104 }
105 task2.hpp:
106 #include "GradeCalc.hpp"
107 #include <iomanip>
108
109 void test() {
110 int n;
111 cout << "输入班级人数: ";
112 cin >> n;
113
114 GradeCalc c1("OOP", n);
115
116 cout << "录入成绩: " << endl;;
117 c1.input();
118 cout << "输出成绩: " << endl;
119 c1.output();
120
121 cout << string(20, '*') + "课程成绩信息" + string(20, '*') << endl;
122 c1.info();
123 }
124
125 int main() {
126 test();
127 }
task2
问题1：
成绩存储在从vector<int>继承而来的容器中；sort方法通过begin()和end()函数就能访问到存储成绩的容器中的每个元素；min方法使用this->begin()和this->end()作为迭代器范围传递给std::min_element函数，以此来遍历存储成绩的容器中的每个元素；max方法与min方法类似；average方法通过this->begin()和this->end()指定要累加的元素范围，也就是存储成绩的容器中的所有成绩元素，然后再除以学生人数n得到平均分；output方法通过一个循环遍历成绩容器。
问题2：
在代码的line68处，分母n的功能是用于计算各分数段人数占总人数的比例；
如果去掉乘以1.0的代码，重新编译和运行，结果会有影响。在原来的代码中，counts.at(i)是int类型，n也是int类型，当进行除法运算counts.at(i) / n时，如果不进行类型转换（乘以1.0就是将其中一个操作数转换为double类型），结果会按照整数除法规则进行计算，即只保留整数部分，小数部分会被截断。
乘以1.0后，会将其中一个操作数隐式转换为double类型，使得除法运算按照浮点数除法规则进行，能得到正确的比例值，保留小数部分，符合统计各分数段比例的需求。
问题3：
在input方法中，没有对用户输入的成绩进行有效性验证。
目前GradeCalc类只考虑了单一课程的成绩统计。在实际应用场景中，可能需要同时处理多门课程的成绩情况。
程序运行结束后，所有输入的成绩数据和计算得到的统计信息都会丢失。
Task3:
1 复制代码
2 #include <iostream>
3 #include <vector>
4 #include <string>
5 #include <algorithm>
6 #include <numeric>
7 #include <iomanip>
8
9 using std::vector;
10 using std::string;
11 using std::cin;
12 using std::cout;
13 using std::endl;
14
15 class GradeCalc {
16 public:
17 GradeCalc(const string &cname, int size);
18 void input(); // 录入成绩
19 void output() const; // 输出成绩
20 void sort(bool ascending = false); // 排序 (默认降序)
21 int min() const; // 返回最低分
22 int max() const; // 返回最高分
23 float average() const; // 返回平均分
24 void info(); // 输出课程成绩信息
25
26 private:
27 void compute(); // 成绩统计
28
29 private:
30 string course_name; // 课程名
31 int n; // 课程人数
32 vector<int> grades; // 课程成绩
33 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]
34 vector<double> rates = vector<double>(5, 0); // 保存各分数段比例
35 };
36
37 GradeCalc::GradeCalc(const string &cname, int size): course_name{cname}, n{size} {}
38
39 void GradeCalc::input() {
40 int grade;
41
42 for(int i = 0; i < n; ++i) {
43 cin >> grade;
44 grades.push_back(grade);
45 }
46 }
47
48 void GradeCalc::output() const {
49 for(int grade: grades)
50 cout << grade << " ";
51 cout << endl;
52 }
53
54 void GradeCalc::sort(bool ascending) {
55 if(ascending)
56 std::sort(grades.begin(), grades.end());
57 else
58 std::sort(grades.begin(), grades.end(), std::greater<int>());
59
60 }
61
62 int GradeCalc::min() const {
63 return *std::min_element(grades.begin(), grades.end());
64 }
65
66 int GradeCalc::max() const {
67 return *std::max_element(grades.begin(), grades.end());
68 }
69
70 float GradeCalc::average() const {
71 return std::accumulate(grades.begin(), grades.end(), 0) * 1.0 / n;
72 }
73
74 void GradeCalc::compute() {
75 for(int grade: grades) {
76 if(grade < 60)
77 counts.at(0)++;
78 else if(grade >= 60 && grade < 70)
79 counts.at(1)++;
80 else if(grade >= 70 && grade < 80)
81 counts.at(2)++;
82 else if(grade >= 80 && grade < 90)
83 counts.at(3)++;
84 else if(grade >= 90)
85 counts.at(4)++;
86 }
87
88 for(int i = 0; i < rates.size(); ++i)
89 rates.at(i) = counts.at(i) *1.0 / n;
90 }
91
92 void GradeCalc::info() {
93 cout << "课程名称:\t" << course_name << endl;
94 cout << "排序后成绩: \t";
95 sort(); output();
96 cout << "最高分:\t" << max() << endl;
97 cout << "最低分:\t" << min() << endl;
98 cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << endl;
99
100 compute(); // 统计各分数段人数、比例
101
102 vector<string> tmp{"[0, 60) ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};
103 for(int i = tmp.size()-1; i >= 0; --i)
104 cout << tmp[i] << "\t: " << counts[i] << "人\t"
105 << std::fixed << std::setprecision(2) << rates[i]*100 << "%" << endl;
106 }
View Code
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
问题1:成绩存储在std::vector<int>这个容器中。min、max、sort、average、output是通过std::vector<int>提供的迭代器接口访问每个成绩。
问题2:类的私有成员变量（如grades、counts、rates等）被隐藏在类的内部，外部代码无法直接访问和修改这些数据，只能通过类提供的公有方法来间接操作。这样可以保证数据的安全性和一致性，防止外部代码无意或恶意地篡改数据，使得程序的行为更加可预测和稳定。
Task4.1:
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 }
1
问题1：
清空输入缓冲区中剩余的字符，特别是换行符等可能影响后续getline函数正确读取的字符。
Task4.2:
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 }
2
Task4.3:
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 }
3
问题2：清空输入缓冲区中剩余的字符，特别是在通过cin >> n读取完整数n后，将可能留在输入缓冲区中的换行符（以及其他可能残留的字符）清除掉。、
Task5:
1 #ifndef GRM_HPP
2 #define GRM_HPP
3
4 template <typename T>
5 class GameResourceManager {
6 private:
7 T resource;
8
9 public:
10 // 带参数的构造函数，初始化当前资源数量
11 GameResourceManager(T initialResource) : resource(initialResource) {}
12
13 // 获取当前的资源数量
14 T get() const {
15 return resource;
16 }
17
18 // 更新当前的资源数量（增加、减少）
19 // 当资源数量减少到<0时，则归0
20 void update(T change) {
21 resource += change;
22 if (resource < 0) {
23 resource = 0;
24 }
25 }
26 };
27
28 #endif
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
Task6:
1 #pragma once
2 #include <iostream>
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 nickname, string contact, string city, int n) {
12 this->nickname = nickname;
13 this->contact = contact;
14 this->city = city;
15 this->n = n;
16 }
17 void display() {
18 cout << "昵称： " << nickname << endl;
19 cout << "联系方式：" << contact << endl;
20 cout << "所在城市：" << city << endl;
21 cout << "预定人数：" << n << endl;
22 cout << string(70, '-') << endl;
23 }
24 };
info
1 #include"info.hpp"
2 #include <vector>
3 using namespace std;
4 int main() {
5 const int capacity = 100;
6 vector<info>audience_lst;
7 int capacity1 = 0;
8 string nickname;
9 string contact;
10 string city;
11 int n;
12 cout << "昵称" + string(5, ' ') + "联系方式（邮箱/手机号）" + string(5, ' ') + "所在城市" + string(5, ' ') + "预定参加人数\n";
13 while (cin >> nickname>>contact>>city>>n) {
14 cin.ignore(numeric_limits<streamsize>::max(), '\n');
15 capacity1 += n;
16 if (capacity1 > capacity) {
17 capacity1 -= n;
18 string choose;
19 cout << "对不起，只剩下" << capacity - capacity1 << "个位置.\n"
20 << "1.输入u，更新（update）预定信息\n"
21 << "2.输入q，退出预定\n"
22 << "你的选择：";
23 cin >> choose;
24 if (choose == "u") {
25 cout << "请重新输入预定信息：\n";
26 continue;
27 }
28 else
29 {
30 break;
31 }
32 }
33 info livehouse(nickname, contact, city, n);
34 audience_lst.push_back(livehouse);
35 if (capacity1 == capacity) { break; }
36 }
37 cout << "截至目前，一共有" << capacity1 << "位听众预约。预约听众的信息如下：\n";
38 cout << string(70, '-') << endl;
39 for (auto& i : audience_lst) {
40 i.display();
41 }
42 return 0;
43 }
View Code
Task7:
1 #ifndef __DATE_H__
2 #define __DATE_H__
3
4 class Date {
5 private:
6 int year; //年
7 int month; //月
8 int day; //日
9 int totalDays; //该日期是从公元元年1月1日开始的第几天
10 public:
11 Date(int year, int month, int day); //用年、月、日构造日期
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 //计算两个日期之间相差多少天
21 int distance(const Date& date) const {
22 return totalDays - date.totalDays;
23 }
24 };
25 #endif
date.h
#include "date.h"
#include <iostream>
#include <cstdlib>
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();
}
date.cpp
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 double getSum(const Date& date) const {
12 return sum + value * date.distance(lastDate);
13 }
14 void change(const Date& date, double value) {
15 sum = getSum(date);
16 lastDate = date;
17 this->value = value;
18 }
19 void reset(const Date& date, double value) {
20 lastDate = date;
21 this->value = value;
22 sum = 0;
23 }
24 };
25 #endif
accumulator.h
1 #ifndef _ACCOUNT_H_
2 #define _ACCOUNT_H_
3 #include "date.h"
4 #include "accumulator.h"
5 #include <string>
6 class Account {
7 private:
8 std::string id;
9 double balance;
10 static double total;
11 protected:
12 Account(const Date& date, const std::string& id);
13 void error(const std::string& msg) const;
14 void record(const Date& data, double amount,const std::string& desc);
15 public:
16 const std::string& getId() const { return id; }
17 double getBalance() const { return balance; }
18 static double getTotal() { return total; }
19 void show() const;
20 };
21 class SavingsAccount : public Account {
22 private:
23 Accumulator acc;
24 double rate;
25 public:
26 SavingsAccount(const Date& date, const std::string& id, double rate);
27 double getRate() const { return rate; }
28 void deposit(const Date& date, double amount, const std::string& desc);
29 void withdraw(const Date& date, double amount, const std::string& desc);
30 void settle(const Date& date);
31 };
32 class CreditAccount : public Account {
33 private:
34 Accumulator acc;
35 double credit;
36 double rate;
37 double fee;
38 double getDebt()const {
39 double balance = getBalance();
40 return (balance < 0 ? balance : 0);
41 }
42 public:
43 CreditAccount(const Date& date, const std::string& id, double credit, double rate, double fee);
44 double getCredit() const { return credit; }
45 double getRate() const { return rate; }
46 double getFee() const { return fee; }
47 double getAvailableCredit() const { return credit; }
48 void deposit(const Date& date, double amount, const std::string& desc);
49 void withdraw(const Date& date, double amount, const std::string& desc);
50 void settle(const Date& date);
51 void show() const;
52 };
53 #endif
acount.h
1 #include "account.h"
2 #include <iostream>
3 #include <cmath>
4 using namespace std;
5 double Account::total = 0;
6
7 // Account类的实现
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;
15 balance += amount;total += amount;
16 date.show();
17 cout << "\t#" << id << "\t" << amount << "\t" << balance << "\t" << desc << endl;
18 }
19
20 void Account::show() const {
21 cout << id << "\tBalance: " << balance;
22 }
23
24 void Account::error(const string& msg) const {
25 cout << "Error(#" << id << "): " << msg << endl;
26 }
27
28 // SavingsAccount类相关成员函数的实现
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 }
41 else {
42 record(date, -amount, desc);
43 acc.change(date, getBalance());
44 }
45 }
46
47 void SavingsAccount::settle(const Date& date) {
48 double interest = acc.getSum(date) * rate/date.distance(Date(date.getYear()-1,1,1));
49 if (interest != 0)
50 record(date, interest, "interest");
51 acc.reset(date, getBalance());
52 }
53
54 // CreditAccount类相关成员函数的实现
55 CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee) :
56 Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) {}
57
58
59 void CreditAccount::deposit(const Date& date, double amount, const string& desc) {
60 record(date, amount, desc);
61 acc.change(date, getDebt());
62 }
account.cpp
1 #include "account.h"
2 #include <iostream>
3 using namespace std;
4
5 int main() {
6 Date date(2008, 11, 1);
7
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 return 0;
31 }
7-10
标签：std,const,int,void,实验,date,include From： https://www.cnblogs.com/g055140/p/18566208