实验四
task1：
代码：
#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(); }
#include <iostream> #include <string> using std::cout; using std::endl; using std::string; // 定义类模板 template<typename T> class X{ public: X(T x0, T y0); void display(); private: T x, 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中的抽象类型T用int实例化" << endl; X<int> x1(3, 4); x1.display(); cout << endl; cout << "测试2: 类模板X中的抽象类型T用double实例化" << endl; X<double> x2(3.2, 5.6); x2.display(); cout << endl; cout << "测试3: 类模板X中的抽象类型T用string实例化" << endl; X<string> x3("hello", "oop"); x3.display(); } int main() { test(); }
#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 }
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task2:
代码：
#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(); }
#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; }
成绩存储在继承来的vector的动态数组中，用this指针访问；
分母用来求取平均值，去掉*1.0答案就会变成整数，整数与整数的运算只能得到整数；
缺乏对数据合理性的判断。
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task3：
代码：
#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(); }
#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; }
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存储在vector的动态数组中，通过变量名加"."的方式访问；
在适合的情况下利用继承与模板类，不一定需要继承。
task4：
代码：
#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(); }
#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(); }
#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(); }
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清空缓冲区的内容，消除上一次输入对下一次输入的影响（问题一同问题二）。
task5：
代码：
#pragma once #include<iostream> using namespace std; template<typename T> class GameResourceManager { private: T resouce; public: GameResourceManager(T Resource):resouce(Resource) {} T get()const { return resouce; } void update(T num) { resouce += num; if (resouce < 0) resouce = 0; } };
#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(); }
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task6:
代码：
#include<iostream> #include<iomanip> using namespace std; class Info{ private: string nickname; string contact; string city; int n; public: Info(string nickname,string contact,string city,int n); void display() const; }; Info::Info(string name,string con,string c,int n1) { nickname=name; contact=con; city=c; n=n1; } void Info::display() const { cout<<setw(20)<<left<<"昵称:"<<nickname<<endl; cout<<setw(20)<<left<<"联系方式:"<<contact<<endl; cout<<setw(20)<<left<<"所在城市:"<<city<<endl; cout<<setw(20)<<left<<"预定人数:"<<n<<endl; }
#include "Info.hpp" #include <iostream> #include<vector> using namespace std; const int capacity=100; int main () { vector<Info> audience_lst; cout<<"录入用户预约信息:"<<endl<<endl; cout<<setw(10)<<left<<"昵称"; cout<<setw(30)<<left<<"联系方式(邮箱/手机号)"; cout<<setw(20)<<left<<"所在城市"; cout<<setw(10)<<left<<"预定参加人数"<<endl; int now_capacity=0; string nickname,contact,city; int n; while(now_capacity<capacity && cin>>nickname>>contact>>city>>n) { now_capacity+=n; if (now_capacity<=capacity) { audience_lst.push_back(Info(nickname,contact,city,n)); } else { now_capacity-=n; cout<<"对不起,只剩80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; cout<<"你的选择:"; char choose; cin>>choose; if (choose=='u') { cout<<"请重新输入预定信息:"<<endl; continue; } else if(choose=='q') { break; } } } cout<<"截至目前，一共有"<<now_capacity<<"为听众预约。预约听众信息如下:"<<endl; int len=audience_lst.size(); for (int i=0;i<len;i++) { cout<<string(50,'-')<<endl; audience_lst[i].display(); } }
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task7:
代码：
#pragma once 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; } };
#pragma once #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; sum = 0; } };
#pragma once #include"date.h" #include"accumulator.h" #include<string> using namespace std; class Account { private: string id; double balance; static double total; protected: Account(const Date& date, const string &id); void record(const Date& date, double amount, const string& desc); void error(const string& msg) const; public:const string& getId() { 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 string& id, double rate); double getRate() const { return rate; } void deposit(const Date& date, double amount, const string& desc); void withdraw(const Date& date, double amount, const 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 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 string& desc); void withdraw(const Date& date, double amount, const string& desc); void settle(const Date& date); void show()const; };
#include"date.h" #include<iostream> #include<cstdlib> using namespace std; namespace { const int DAYS_BEFIRE_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_BEFIRE_MONTH[month - 1] + day; if (isLeapYear() && month > 2) totalDays++; } int Date::getMaxDay()const { if (isLeapYear() && month == 2) return 29; else return DAYS_BEFIRE_MONTH[month] - DAYS_BEFIRE_MONTH[month - 1]; } void Date::show()const { cout << getYear() << "-" << getMonth() << "-" << getDay(); }
#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 enouogh 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; }
截图：
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.复用性较差。
