任务二：
GradeCalc.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: 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 }
demo2.cpp:
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：成绩存储在vector中，通过begin()和end()接口访问到每个成绩，input通过push_back实现数据存入对象
问题2：分母功能除以总数获取平均值，有影响，*1.0将数据转换成浮点数型，不乘的话默认int整除int
问题3：成绩的合法性没有检验
任务三：
demo3.cpp:
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 }
GradeCalc.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 }
问题1：成绩储存在类中grade变量里，通过访问grade对象访问成绩
问题2：面向对象编程可以完全按照需求设计自己想要的类
任务四：
task4_1.cpp:
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 }
问题1：cin.ignore()函数中有两个参数，分别为数值型的a 和 字符型的 ch ，即cin.ignore( a, ch )。它表示从输入流 cin 中提取字符，提取的字符被忽略，不被使用。而每抛弃一个字符，它都要进行计数和比较字符：如果计数值达到 a 或者被抛弃的字符是 ch ，则cin.ignore() 函数执行终止；否则，它继续等待。
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 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 }
task4-3:
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 }
问题二：line16的作用是清除输入缓冲区中的剩余字符，防止输入操作出现错误。去掉这行代码程序可能因为输入缓冲区中的遗留字符而出现错误。
任务五：
grm.hpp:
1 #include <iostream> 2 3 using namespace std; 4 template<typename T> 5 class GameResourceManager{ 6 private: 7 T resource; 8 9 public: 10 GameResourceManager(T a):resource(a){} 11 T get(){ 12 return resource; 13 14 } 15 void update(T b){ 16 resource += b; 17 if(resource<0) resource=0; 18 19 } 20 };
task5:
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 }
任务六：
info.hpp：
1 #include <iostream> 2 #include <string> 3 4 using namespace std; 5 class Info{ 6 private: 7 string name; 8 string contact; 9 string city; 10 int num; 11 12 public: 13 Info(string name,string contact,string city,int num):name(name),contact(contact),city(city),num(num){} 14 void display(){ 15 cout<<"昵称："<<name<<endl; 16 cout<<"联系方式："<<contact<<endl; 17 cout<<"城市："<<city<<endl; 18 cout<<"预定人数"<<num<<endl; 19 20 } 21 22 23 };
task6:
1 #include "info.hpp" 2 #include <iostream> 3 #include <vector> 4 #include<limits> 5 6 using namespace std; 7 8 int main() 9 { 10 const int capacity = 100; 11 vector<Info> infolist; 12 string name,contact,city; 13 int num,left=capacity; 14 char choice; 15 16 cout<<"昵称 "<<"联系方式(邮箱/手机号) "<<"所在城市 "<<"预定参加人数"<<endl; 17 while(1) 18 { 19 cin>>name>>contact>>city>>num; 20 cin.ignore(numeric_limits<streamsize>::max(), '\n'); 21 if(left<num) 22 { 23 cout<<"对不起，只剩"<<left<<"个位置了"<<endl; 24 cout<<"输入u,更新预定信息"<<endl; 25 cout<<"输入q,退出"<<endl; 26 cout<<"请输入您的选择："; 27 cin>>choice; 28 if(choice=='u') continue; 29 else break; 30 } 31 else 32 { 33 infolist.push_back(Info(name,contact,city,num)); 34 left-=num; 35 36 } 37 } 38 cout<<"截至目前，一共有" << capacity-left << "位听众预约。预约听众信息如下:\n"; 39 cout<<"------------------------------"<<endl; 40 for(auto i:infolist){ 41 i.display(); 42 cout<<"------------------------------"<<endl; 43 44 } 45 return 0; 46 }
任务七：
date.h：
1 #pragma once 2 #ifndef DATE H 3 #define DATE H 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 int distance(const Date& date)const { 21 return totalDays - date.totalDays; 22 } 23 }; 24 #endif// DATE H.
date.cpp:
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 Date::Date(int year, int month, int day) :year{ year }, month{ month }, day{ day } { 9 if (day <= 0 || day > getMaxDay()) { 10 cout << "Invalid date:"; 11 show(); 12 cout << endl; 13 exit(1); 14 } 15 int years = year - 1; 16 totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day; 17 if (isLeapYear() && month > 2)totalDays++; 18 } 19 int Date::getMaxDay()const { 20 if (isLeapYear() && month == 2) 21 return 29; 22 else return DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1]; 23 } 24 25 void Date::show()const { 26 cout << getYear() << "-" << getMonth() << "-" << getDay(); 27 }
account.h：
1 #pragma once 2 #ifndef ACCOUNT H 3 #define ACCOUNT H 4 #include"date.h" 5 #include"accumulator.h" 6 #include<string> 7 class Account { 8 private: 9 std::string id; 10 double balance; 11 static double total; 12 protected: 13 Account(const Date& date, const std::string& id); 14 void record(const Date& date, double amount, const std::string& desc); 15 void error(const std::string& msg)const; 16 public: 17 const std::string& getId()const { return id; } 18 double getBalance()const { return balance; } 19 static double getTotal() { return total; } 20 21 void show()const; 22 }; 23 class SavingsAccount :public Account { 24 private: 25 Accumulator acc; 26 double rate; 27 public: 28 SavingsAccount(const Date& date, const std::string& id, double rate); 29 double getRate()const { return rate; } 30 31 void deposit(const Date& date, double amount, const std::string& desc); 32 void withdraw(const Date& date, double amount, const std::string& desc); 33 void settle(const Date& date); 34 }; 35 class CreditAccount :public Account { 36 private: 37 Accumulator acc; 38 double credit; 39 double rate; 40 double fee; 41 double getDebt()const { 42 double balance = getBalance(); 43 return (balance < 0 ? balance : 0); 44 } 45 public: 46 CreditAccount(const Date& date, const std::string& id, double credit, double rate, double fee); 47 double getCredit()const { return credit; } 48 double getRate()const { return rate;} 49 double getAvailableCredit()const { 50 if (getBalance() < 0) 51 return credit + getBalance(); 52 else 53 return credit; 54 } 55 void deposit(const Date& date, double amount, const std::string& desc); 56 void withdraw(const Date& date, double amount, const std::string& desc); 57 void settle(const Date& date); 58 void show()const; 59 }; 60 #endif//ACCOUNT H
accumulator.h：
1 #pragma once 2 #ifndef ACCUMULATOR H 3 #define ACCUMULATOR H 4 #include"date.h" 5 class Accumulator { 6 private: 7 Date lastDate; 8 double value; 9 double sum; 10 public: 11 Accumulator(const Date& date, double value) :lastDate(date), value(value), sum{ 0 } { 12 } 13 14 double getSum(const Date& date)const { 15 return sum + value * date.distance(lastDate); 16 } 17 18 void change(const Date& date, double value) { 19 sum = getSum(date); 20 lastDate = date; this->value = value; 21 } 22 23 void reset(const Date& date, double value) { 24 lastDate = date; this->value = value; sum = 0; 25 } 26 }; 27 #endif//ACCUMULATOR H
task7：
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 return 0; 31 }
