任务一:
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();
}
实验结果截图
task1_2.cpp:
#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();
}
实验结果截图
任务二：
GradeCale.hpp:
#pragma once
#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());elsestd::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;
}
taks2.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();
}
实验结果截图：
问题1：派生类GradeCalc定义中，成绩存储在哪里？派生类方法sort, min, max, average, output都要访问成绩，是通过什么接口访问到每个成绩的？input方法是通过什么接口实现数 据存入对象的？
答：成绩储存在GradeCale类的基类vector<int>中，派生类方法通过继承自vector<int>的接口访问成绩，input通过vector<int>中的push_back方法实现数据岑如对象。
问题2：代码line68分母的功能是？去掉乘以1.0代码，重新编译、运行，结果有影响吗？为什 么要乘以1.0？
答：分母的功能是计算平均值。有影响，乘1.0会是分子强制变成浮点数，防止出现整数除法导致精度丢失的情况。
问题3：从真实应用场景角度考虑，GradeCalc类在设计及代码实现细节上，有哪些地方尚未 考虑周全，仍需继续迭代、完善？
答：可以增加数据验证功能，验证用户输入的数据是否合法，出现异常时能及时给予错误信息。可以考虑加入一些提示信息，使用户使用更加便捷。
任务三：
GradeCale.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());elsestd::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();
}
实验结果截图：
问题1：组合类GradeCalc定义中，成绩存储在哪里？组合类方法sort, min, max, average, output都要访问成绩，是通过什么接口访问到每个成绩的？观察与实验任务2在代码写法细节 上的差别。
答：成绩储存在类型为vector<int>的成员变量grade中，这些组合类方法都通过访问grade来访问成绩。
问题2：对比实验任务2和实验任务3，主体代码逻辑（测试代码）没有变更，类GradeCalc的 接口也没变，变化的是类GradeCalc的设计及接口内部实现细节。你对面向对象编程有什么新 的理解和领悟吗？
答：即使外部接口不变，也可以通过内部调整来适应新的需求。
任务四：
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();
}
实验结果截图：
问题1：去掉task4_1.cpp的line35，重新编译、运行，给出此时运行结果截图。查阅资料，回答 line35在这里的用途是什么？
答:这是一种确保输入正确处理的通用方法。它帮助清理输入流，避免后续输入受到跨行输入或多余字符的影响
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();
}
实验结果截图：
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();
}
实验结果截图：
问题2：去掉task4_3.cpp的line16，重新编译、运行，给出此时运行结果。查阅资料，回答line16 在这里的用途是什么？
答：清理cin>>n后的回车键，防止录入回车。
任务五：
grm.hpp:
#pragma once#include <iostream>
using namespace std;
template<typename T>
class GameResourceManager {
public:GameResourceManager(T x);T get();void update(T x);private:T resource;
};
template<typename T>
GameResourceManager<T>::GameResourceManager(T x) {resource = x;
}
template<typename T>
T GameResourceManager<T>::get() {return resource;
}
template<typename T>
void GameResourceManager<T>::update(T x) {resource += x;
}
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();
}
实验结果截图：
任务六：
info.hpp:
#pragma once
#include <iostream>
#include <string>using std::string;
using std::cout;
using std::endl;class Info {
public:Info(const string& nickname, const string& contact, const string& city, int num): nickname(nickname), contact(contact), city(city), number(num) {}void display() const {cout << "昵称:\t" << nickname << endl;cout << "联系方式:\t" << contact << endl;cout << "所在城市:\t" << city << endl;cout << "预定人数:\t" << number << endl;}private:string nickname;string contact;string city;int number;
};
task6.cpp:
#include "info.hpp"
#include <iostream>
#include <vector>
#include <string>
#include <limits>using std::vector;
using std::string;
using std::cin;
using std::cout;
using std::endl;int main() {const int capacity = 100;vector<Info> audience_lst;int total_reserved = 0;while (true) {cout << "请输入用户预约信息: " << endl;string nickname, contact, city;int num;cout << "昵称:";cin >> nickname;cout << "联系方式（邮箱/手机号）:";cin >> contact;cout << "所在城市:";cin >> city;cout << "预定参加人数:";cin >> num;if (total_reserved + num > capacity) {cout << "对不起，只剩下" << (capacity - total_reserved) << "个位子。" << 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 choice;cin >> choice;if (choice == 'q') {break;}else if (choice == 'u') {cout << "请重新输入预定信息:" << endl;continue; // 返回循环重新输入}}audience_lst.emplace_back(nickname, contact, city, num);total_reserved += num;if (total_reserved >= capacity) {cout << "预约已满!" << endl;break;}}cout << "截至目前，一共有" << total_reserved << "位听众预约。预约听众信息如下：" << endl;cout << "-----------------------------------------------------" << endl;for (const auto& info : audience_lst) {info.display();cout << "-----------------------------------------------------" << endl;}return 0;
}
实验结果截图：
实验七：
account.h:
//account.h
#ifndef _ACCOUNT_H_
#define _ACCOUNT_H_#include "date.h"
#include "accumulator.h"
#include <string>
class Account { //账户类
private:std::string id; //账号double balance; //余额 static double total;//所有账户的总金额 protected://供派生类调用的构造函数，id为账户 Account(const Date& date, const std::string& id);//记录一笔账，date为日期，amount为金额，desc为说明 void record(const Date& date, double amount, const std::string& desc);//报告错误信息 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; }//显示账户信息 void show() const;
};
//////////class SavingsAccount : public Account {//储账户类 private:Accumulator acc; //辅助计算利息的累加器 double rate; //存款的年利率 public://构造函数 SavingsAccount(const Date& date, const std::string& id, double rate);double getRate() const { return rate; }//存入现金 void deposit(const Date &date, double amount, const std::string& desc);//取出现金 void withdraw(const Date& date, double amount, const std::string& desc);void settle(const Date &date); //结算利息，每年1月1日调用一次该函数};class CreditAccount :public Account {//信用账户类 private:Accumulator acc; //辅助计算利息的累加器 double credit; //信用额度 double rate; //欠款的日利率 double fee; //信用卡年费 double getDebt() const { //获得欠款额 double balance = getBalance();return (balance < 0 ? balance : 0); }public://构造函数 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 {//获得可用信用if (getBalance() < 0)return credit + getBalance();elsereturn credit;}//存入现金void deposit(const Date& date, double amount, const std::string& desc);//取出现金void withdraw(const Date& date, double amount, const std::string& desc);void settle(const Date& date); //结算利息和年费，每月1日调用一次该函数void show() const;};
#endif // _ACCOUNT_H_
accumulator.h:
// accumulator.h
#ifndef _ACCUMULATOR_H_
#define _ACCUMULATOR_H_#include "date.h"class Accumulator {
private:Date lastDate;double value;double sum;public:// 构造函数，date为开始累加的日期，value为初始值Accumulator(const Date& date, double value) : lastDate(date), value(value), sum(0) {}// 获取到日期date的累加结果double getSum(const Date& date) const {return sum + value * date.distance(lastDate);}// 在date将数值变更为valuevoid change(const Date& date, double value) {sum = getSum(date);lastDate = date;this->value = value;}// 初始化，将日期变为date，数值变为value，累加器清零void reset(const Date& date, double value) {lastDate = date;this->value = value;sum = 0;}
};#endif // _ACCUMULATOR_H_
date.h:
// accumulator.h
#ifndef _ACCUMULATOR_H_
#define _ACCUMULATOR_H_#include "date.h"class Accumulator {
private:Date lastDate;double value;double sum;public:// 构造函数，date为开始累加的日期，value为初始值Accumulator(const Date& date, double value) : lastDate(date), value(value), sum(0) {}// 获取到日期date的累加结果double getSum(const Date& date) const {return sum + value * date.distance(lastDate);}// 在date将数值变更为valuevoid change(const Date& date, double value) {sum = getSum(date);lastDate = date;this->value = value;}// 初始化，将日期变为date，数值变为value，累加器清零void reset(const Date& date, double value) {lastDate = date;this->value = value;sum = 0;}
};#endif // _ACCUMULATOR_H_
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;elsereturn DAYS_BEFORE_MONTH[month] - DAYS_BEFORE_MONTH[month - 1];
}
void Date::show() const {cout << getYear() << "-" << getMonth() << "-" << getDay();
}
accumulator.cpp:
//account.cpp
#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double Account::total = 0;
//Account类的实现
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;//保留小数点后两位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类相关成员函数的实现
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; // 计算年息// 假设date距离Date(date.getYear() - 1, 1, 1)的距离是1if (interest != 0) {record(date, interest, "interest");acc.reset(date, getBalance());}
}// CreditAccount 类相关成员函数的实现
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) {if (amount - getBalance() > credit) {error("not enough credit");}else {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) {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:
//7_10.cpp
#include "account.h"
#include <iostream>
using namespace std;int main() {Date date(2008, 11, 1); // 起始日期// 建立几个账户SavingsAccount sal(date, "S3755217", 0.015);SavingsAccount sa2(date, "02342342", 0.015);CreditAccount ca(date, "C5392394", 10000, 0.0005, 50);// 11月份的几笔账目sal.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");// 结算信用卡ca.settle(Date(2008, 12, 1));// 12月份的几笔账目ca.deposit(Date(2008, 12, 1), 2016, "repay the credit");sal.deposit(Date(2008, 12, 5), 5500, "salary");// 结算所有账户sal.settle(Date(2009, 1, 1));sa2.settle(Date(2009, 1, 1));ca.settle(Date(2009, 1, 1));// 输出各个账户信息cout << endl;sal.show();cout << endl;sa2.show();cout << endl;ca.show();cout << endl;cout << "Total: " << Account::getTotal() << endl;return 0;
}
实验结果截图:
