实验4 类的组合、继承、模板类、标准库
实验任务1：
task1_1.cpp
#include <iostream> using std::cout; using std::endl; // 类A的定义 class A { public: A(int x0, int y0); void display() const; private: int x, y; }; A::A(int x0, int y0) : x{ x0 }, y{ y0 } { } void A::display() const { cout << x << ", " << y << endl; } // 类B的定义 class B { public: B(double x0, double y0); void display() const; private: double x, y; }; B::B(double x0, double y0) : x{ x0 }, y{ y0 } { } void B::display() const { cout << x << ", " << y << endl; } void test() { cout << "测试类A: " << endl; A a(3, 4); a.display(); cout << "\n测试类B: " << endl; B b(3.2, 5.6); b.display(); } int main() { test(); }
运行测试结果：
task1_2.cpp
#include<iostream> #include<string> using std::cout; using std::endl; using std::string; template<typename T> class X { public: X(T x0, T y0); void display(); private: T x; T y; }; template<typename T> X<T>::X(T x0, T y0) :x{ x0 }, y{ y0 } {} template<typename T> void X<T>::display() { cout << x << "," << y<<endl; } void test() { cout << "测试1：类模板X的抽象类型T用int实例化" << endl; X<int> x1(3, 4); x1.display(); cout << endl; cout << "测试1：类模板X的抽象类型T用double实例化" << endl; X<double> x2(3.2, 5.6); x2.display(); cout << endl; cout << "测试1：类模板X的抽象类型T用string实例化" << endl; X<string> x3("hello", "opp"); x3.display(); } int main() { test(); }
运行测试结果：
task1_3cpp
#include <complex> #include <vector> #include <array> int main() { using namespace std; complex<double> x1(5, 3); // complex类模板，特化到double类型 vector<int> x2{ 1, 9, 8, 4 }; // vector类模板，特化到int类型 array<int, 4> x3{ 1,9, 8, 4 }; // array类模板，特化到int类型 // 其它略 }
实验任务2：
GradeCalc.hpp
#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; }
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(); }
运行测试结果：
问题1：
GradeCalc 直接继承 vector<int>,成绩直接存储在GradeCalc中
sort：this->begin()和this->end()访问成绩数组的开始和末尾位置，然后调用std::sort进行排序
min:用std::min_element访问成绩数组最小元素
max:用std::max_element访问成绩数组最大元素
average:用std::accumulate实现对成绩数组元素的求和，然后除以学生总数n，求出average
output:是利用this->begin()和this->end()迭代输出每个学生的成绩
input：是通过this->push_back(grade)存入成绩
问题2：
line68分母的功能是：除以n后可以求得成绩的平均值
去掉*1.0前平均值输出80.20，去掉后输出80.00。
因为成绩和是int类型，*1.0可以把成绩转化为浮点数，如果去掉，将会损失平均值的小数部分
问题3：
没有对输入的成绩进行检查，应该使成绩在0~100之间，如果输入的成绩不在这个范围内，会报错提醒
实验任务3：
GradeCalc.hpp
#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: 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(); }
运行测试结果：
问题1：
Gradecalc不继承 vector<int>,而是用vector<int> 一个成员变量grades存储成绩，是一个组合方式
sort:从grades.begin()迭代到grades.end()，利用std::sort对grades数组中的成绩进行排序
min:用std::min_element访问grades数组中的最小值
max:用std::max_element访问grades数组中的最大值
average:用std::accumulate对grades数组中的元素进行求和，再除以学生总数n求得平均成绩
output:遍历gardes数组
问题2：
组合由于继承，直接把grades封装在了GradeCalc的内部，外部无法访问，并且更便于修改
实验任务4：
task4_1.cpp
#include <iostream> #include <string> #include <limits> 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; cin.ignore(numeric_limits<streamsize>::max(), '\n'); 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(); }
运行测试结果：
问题1：
删除在调用 test2 和 test3 之前，残留的换行符或其他字符
task4_2.cpp
#include <iostream> #include <string> #include <vector> #include <limits> 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(); }
运行测试结果：
task4_3.cpp
#include <iostream> #include <string> #include <vector> #include <limits> 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(); }
运行测试结果：
问题2：
line16的作用是删除输入v2之前，残留的换行符
实验任务5：
grm.hpp
#include<iostream> using namespace std; using std::cout; using std::endl; template<typename T> class GameResourceManager { public: GameResourceManager(T r); T get() const; void update(T value); private: T resource; }; template<typename T> GameResourceManager<T>::GameResourceManager(T r):resource{r}{} template<typename T> T GameResourceManager<T>::get() const { 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(); }
运行测试结果：
实验任务6：
info.hpp
#include<iostream> #include<string> using namespace std; using std::cout; using std::endl; using std::string; class Info { public: Info(string nickname0, string contact0, string city0, int n0); void display() const; private: string nickname; string contact; string city; int n; }; Info::Info(string nickname0, string contact0, string city0, int n0): nickname{nickname0},contact{contact0},city{city0},n{n0}{} void Info::display() const { 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; }
task6.cpp
#include"info.hpp" #include<iostream> #include<vector> #include<limits> #include<string> using std::cin; using std::cout; using std::endl; using std::string; using std::vector; int main() { const int capacity = 100; vector<Info> audience_lst; int total = 0; while (1) { string nickname, contact, city; int n; cout << "录入用户信息：" << endl; 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" << " \t " << endl; cin >> nickname; cout << " \t "; cin >> contact; cout << " \t "; cin >> city; cout << " \t "; cin >> n; cout << endl; if (n + total > capacity) { cout << "对不起，只剩" << capacity - total << "个位置" << endl; cout << "1. 输入 u，更新（update）预定信息" << endl; cout << "2. 输入 q，退出预定" << endl; char choice; cin >> choice; cout << "你的选择：" << choice << endl; if (choice == 'u') { cout << "请重新输入预定信息：" << endl; continue; } if (choice == 'q') { break; } } audience_lst.emplace_back(nickname, contact, city, n); total = total + n; cout << "截至目前，一共有" << total << "位听众预约，预约听众信息如下：" << endl; cout << string(40, '-') << endl; for (const auto& info : audience_lst) { info.display(); cout << string(40, '-') << endl; } if (total >= capacity) { cout << "已经达到预定上限，不再接受新的预约。" << endl; break; } } return 0; }
运行测试结果：
实验任务7：
date.h
#ifndef _DATE_H_ #define _DATE_H_ class Date { private: int year; int month; int day; int totalDays; public: Date(int year, int month, int day); 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<iostream> #include<cstdlib> using namespace std; namespace { 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 { //将某个数值按日累加 private: Date lastDate; //上次变更数值的日期 double value; //数值的当前值 double sum; //数值按日累加之和 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"date.h" #include"accumulator.h" #include<string> class Account { private: std::string id; //账号 double balance; //余额 static double total; //所有账户的总金额 protected: Account(const Date& date, const std::string& id); void record(const Date& date, double amount, const std::string& desc); void error(const std::string& msg)const; 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 { //存储账户类 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);//结算利息，每年一月一日调用一次该函数 }; class CreditAccount :public Account { //信用账户类 private: Accumulator acc; double credit; double rate; double fee; double getDebt() const { //获得欠款额 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 { if (getBalance() < 0) { return credit + getBalance(); } else 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::Account(const Date& date, const std::string& id) :id(id), balance(0) { date.show(); cout << "\t#" << id << " created" << endl; } void Account::record(const Date& date, double amount, const std::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::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 std::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::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()); } void CreditAccount::withdraw(const Date &date,double amount ,const string &desc){ if (amount - getBalance() > credit) { error("not enough credit"); } else { record(date, -amount, desc); acc.change(date, getDebt()); } } void CreditAccount::settle(const Date& date) { double interest = acc.getSum(date) * rate; if (interest != 0) record(date, interest, "interest"); if (date.getMonth() == 1) record(date, -fee, "annual fee"); acc.reset(date, getDebt()); } void CreditAccount::show() const { Account::show(); cout << " \tAvailable credit:" << getAvailableCredit(); }
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, 5), 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; }
运行测试结果：
每个派生类都将基类的成员原样继承过来，例如最后在输出各个账户信息信息时，只能分别调用show函数，不能像第六章那样通过循环来进行
