实验四 类的组合、继承、模板类、标准库
任务2：
#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; }
#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(); }
运行结果：
问题1：成绩存在vector容器中；通过this指针访问到begin(),end()访问成绩；input通过push_back（grade)实现数据存入对象
问题2：求平均值；有影响，乘完之后数据变为浮点形式，确保精度
问题3：没有对成绩是否合法进行检验
任务3：
#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; }
#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(); }
运行结果：
问题1：存储在vector容器中；通过grades.()访问对象来访问成绩
问题2：面向对象编程可以按照需求设计自己想要的类
任务4：
#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(); }
运行结果：
问题1：
删除后的运行结果：
cin.ignore()函数作用是从输入流 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。它的主要功能跳过输入流中的某些字符，使其不会对后续的输入内容产生干扰。
#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(); }
运行结果：
#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(); }
运行结果：
问题2：
删除后运行结果为：
作用是清除输入缓冲区中的剩余字符，防止输入因缓冲区遗留数据发生错误。去掉这行代码程序可能因为输入缓冲区中有遗留数据出现错误。
任务5：
#ifndef GRM_HPP #define GRM_HPP template <typename T> class GameResourceManager { private: T resource; public: GameResourceManager(T initial) : resource(initial) {} T get() { return resource; } void update(T change) { resource += change; if (resource < 0) { resource = 0; } } }; template <> class GameResourceManager<int> { private: int resource; public: GameResourceManager(int initial) : resource(initial) {} int get() { return resource; } void update(int change) { resource += change; if (resource < 0) { resource = 0; } } }; template <> class GameResourceManager<float> { private: float resource; public: GameResourceManager(float initial) : resource(initial) {} float get() { return resource; } void update(float change) { resource += change; if (resource < 0.0f) { resource = 0.0f; } } }; #endif
#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(); }
运行结果：
任务6：
#ifndef INFO_HPP #define INFO_HPP #include <string> #include <iostream> class Info { private: std::string nickname; std::string contact; std::string city; int n; public: Info(const std::string& nickname, const std::string& contact, const std::string& city, int n) : nickname(nickname), contact(contact), city(city), n(n) {} void display() const { std::cout << "昵称: " << nickname << "\n" << "联系方式: " << contact << "\n" << "所在城市: " << city << "\n" << "预定参加人数: " << n << "\n" << std::endl; } int getN() const { return n; } }; #endif
#include <iostream> #include <vector> #include <string> #include "info.hpp" const int capacity = 100; int main() { std::vector<Info> audience_lst; int totalReserved = 0; std::cout << "请输入预约信息:\n"; while (true) { if (totalReserved >= capacity) { std::cout << "已达到最大预约人数，不能再预约！\n"; break; } std::string nickname, contact, city; int n; std::cout << "请输入昵称: "; std::getline(std::cin, nickname); if (nickname.empty()) break; std::cout << "请输入联系方式 (email/手机号): "; std::getline(std::cin, contact); std::cout << "请输入所在城市: "; std::getline(std::cin, city); std::cout << "请输入预定参加人数: "; std::cin >> n; std::cin.ignore(); if (n <= 0) { std::cout << "预定参加人数不能小于等于0！\n"; continue; } if (totalReserved + n > capacity) { std::cout << "预定人数超过剩余容量！剩余容量: " << capacity - totalReserved << std::endl; std::cout << "请输入 'q' 退出预约，或 'u' 更新预约信息: "; char option; std::cin >> option; std::cin.ignore(); if (option == 'q') { break; } else if (option == 'u') { std::cout << "请输入更新后的预定人数: "; std::cin >> n; std::cin.ignore(); if (n <= 0 || totalReserved + n > capacity) { std::cout << "更新后的预定人数无效，无法更新！\n"; continue; } } } audience_lst.push_back(Info(nickname, contact, city, n)); totalReserved += n; std::cout << "预约成功！当前已预定人数: " << totalReserved << "\n\n"; } std::cout << "\n所有预约的听众信息:\n"; for (const auto& audience : audience_lst) { audience.display(); } return 0; }
运行结果：
任务7：
#pragma once #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; int distance(const Date& date)const { return totalDays - date.totalDays; } }; #endif//
#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(); }
#pragma once #ifndef ACCUMULATOR H #define ACCUMULATOR H #include"date.h" class Accumulator { private: Date lastDate; double value; double sum; 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//
#pragma once #ifndef ACCOUNT H #define ACCOUNT H #include"date.h" #include"accumulator.h" #include<string> class Account { private: std::string id; double balance; static double total; 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 { 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); }; class CreditAccount :public Account { private: Accumulator acc; double credit; double rate; double fee; double getDebt()const { 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 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
#include"account.h" #include<cmath> #include<iostream> using namespace std; double Account::total = 0; Account::Account(const Date& date, const string& id) :id{ id }, balance{ 0 } { date.show(); cout << "\t#" << id << "created" << endl; } void Account::record(const Date& date, double amount, const 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 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(); }
#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, 15), 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; }
运行结果：
