OOP-实验5
一、任务1
1、源代码：
publish.hpp
#pragma once
#include <string>
// 发行/出版物类：Publisher （抽象类）
class Publisher {
public:
Publisher(const std::string &name_ = ""); // 构造函数
virtual ~Publisher() = default;
public:
virtual void publish() const = 0; // 纯虚函数，作为接口继承
virtual void use() const = 0; // 纯虚函数，作为接口继承
protected:
std::string name; // 发行/出版物名称
};
// 图书类: Book
class Book: public Publisher {
public:
Book(const std::string &name_ = "", const std::string &author_ = ""); // 构造函数
public:
void publish() const override; // 接口
void use() const override; // 接口
private:
std::string author; // 作者
};
// 电影类: Film
class Film: public Publisher {
public:
Film(const std::string &name_ = "", const std::string &director_ = ""); // 构造函数
public:
void publish() const override; // 接口
void use() const override; // 接口
private:
std::string director; // 导演
};
// 音乐类：Music
class Music: public Publisher {
public:
Music(const std::string &name_ = "", const std::string &artist_ = "");
public:
void publish() const override; // 接口
void use() const override; // 接口
private:
std::string artist; // 音乐艺术家名称
};publish.cpp
#include <iostream>
#include <string>
#include "publisher.hpp"
// Publisher类：实现
Publisher::Publisher(const std::string &name_): name {name_} {
}
// Book类: 实现
Book::Book(const std::string &name_ , const std::string &author_ ): Publisher{name_}, author{author_} {
}
void Book::publish() const {
std::cout << "Publishing book《" << name << "》 by " << author << '\n';
}
void Book::use() const {
std::cout << "Reading book 《" << name << "》 by " << author << '\n';
}
// Film类：实现
Film::Film(const std::string &name_, const std::string &director_):Publisher{name_},director{director_} {
}
void Film::publish() const {
std::cout << "Publishing film <" << name << "> directed by " << director << '\n';
}
void Film::use() const {
std::cout << "Watching film <" << name << "> directed by " << director << '\n';
}
// Music类：实现
Music::Music(const std::string &name_, const std::string &artist_): Publisher{name_}, artist{artist_} {
}
void Music::publish() const {
std::cout << "Publishing music <" << name << "> by " << artist << '\n';
}
void Music::use() const {
std::cout << "Listening to music <" << name << "> by " << artist << '\n';
}task1.cpp
#include <memory>
#include <iostream>
#include <vector>
#include "publisher.hpp"
void test1() {
std::vector<Publisher *> v;
v.push_back(new Book("Harry Potter", "J.K. Rowling"));
v.push_back(new Film("The Godfather", "Francis Ford Coppola"));
v.push_back(new Music("Blowing in the wind", "Bob Dylan"));
for(Publisher *ptr: v) {
ptr->publish();
ptr->use();
std::cout << '\n';
delete ptr;
}
}
/*
void test2() {
std::vector<std::unique_ptr<Publisher>> v;
v.push_back(std::make_unique<Book>("Harry Potter", "J.K. Rowling"));
v.push_back(std::make_unique<Film>("The Godfather", "Francis Ford Coppola"));
v.push_back(std::make_unique<Music>("Blowing in the wind", "Bob Dylan"));
for(const auto &ptr: v) {
ptr->publish();
ptr->use();
std::cout << '\n';
}
}*/
void test3() {
Book book("A Philosophy of Software Design", "John Ousterhout");
book.publish();
book.use();
}
int main() {
std::cout << "运行时多态：纯虚函数、抽象类\n";
std::cout << "\n测试1: 使用原始指针\n";
test1();
/* std::cout << "\n测试2: 使用智能指针\n";
test2();
*/
std::cout << "\n测试3: 直接使用类\n";
test3();
}
2、运行结果截图：
3、问题1：抽象类机制
（1）是什么决定了 Publisher 是抽象类？用一句话说明，并指出代码中的具体依据。
Publisher类的纯虚函数：virtual void publish const()=0;virtual void use const()=0;
（2）如果在 main.cpp 里直接写 Publisher p; 能否编译通过？为什么？
不能。抽象类中有纯虚函数，不能实例化对象。
4、问题2：纯虚函数与接口继承
（1） Book 、 Film 、 Music 必须实现哪两个函数才能通过编译？请写出其完整函数声明。
void publish const() override；void use const()override；
（2） 在 publisher.cpp 的 Film 类实现中，把两个成员函数实现里的 const 去掉（保持函数体不变），重新编译，报错信息是什么？
5、问题3：运行时多态与虚析构
（1）在 test1() 里， for (Publisher *ptr : v) 中 ptr 的声明类型是什么？
指向基类的指针。
（2）当循环执行到 ptr->publish(); 时， ptr 实际指向的对象类型分别有哪些？（按循环顺序写出）
Book* Film* Music*
（3）基类 Publisher 的析构函数为何声明为 virtual ？若删除 virtual ，执行 delete ptr; 会出现什么问题？
为了调用析构函数是调用的是派生类析构函数，防止内存泄漏；出现只调用基类析构函数而无法delete派生类的情况。
二、任务2
1、源代码：
book.hpp
#pragma once
#include <string>
// 图书描述信息类Book: 声明
class Book {
public:
Book(const std::string &name_,
const std::string &author_,
const std::string &translator_,
const std::string &isbn_,
double price_);
friend std::ostream& operator<<(std::ostream &out, const Book &book);
private:
std::string name; // 书名
std::string author; // 作者
std::string translator; // 译者
std::string isbn; // isbn号
double price; // 定价
};book.cpp
#include <iomanip>
#include <iostream>
#include <string>
#include "book.hpp"
// 图书描述信息类Book: 实现
Book::Book(const std::string &name_,
const std::string &author_,
const std::string &translator_,
const std::string &isbn_,
double price_):name{name_}, author{author_}, translator{translator_}, isbn{isbn_}, price{price_} {
}
// 运算符<<重载实现
std::ostream& operator<<(std::ostream &out, const Book &book) {
using std::left;
using std::setw;
out << left;
out << setw(15) << "书名:" << book.name << '\n'
<< setw(15) << "作者:" << book.author << '\n'
<< setw(15) << "译者:" << book.translator << '\n'
<< setw(15) << "ISBN:" << book.isbn << '\n'
<< setw(15) << "定价:" << book.price;
return out;
}booksale.hpp
#pragma once
#include <string>
#include "book.hpp"
// 图书销售记录类BookSales：声明
class BookSale {
public:
BookSale(const Book &rb_, double sales_price_, int sales_amount_);
int get_amount() const; // 返回销售数量
double get_revenue() const; // 返回营收
friend std::ostream& operator<<(std::ostream &out, const BookSale &item);
private:
Book rb;
double sales_price; // 售价
int sales_amount; // 销售数量
};booksale.cpp
#include <iomanip>
#include <iostream>
#include <string>
#include "booksale.hpp"
// 图书销售记录类BookSales：实现
BookSale::BookSale(const Book &rb_,
double sales_price_,
int sales_amount_): rb{rb_}, sales_price{sales_price_}, sales_amount{sales_amount_} {
}
int BookSale::get_amount() const {
return sales_amount;
}
double BookSale::get_revenue() const {
return sales_amount * sales_price;
}
// 运算符<<重载实现
std::ostream& operator<<(std::ostream &out, const BookSale &item) {
using std::left;
using std::setw;
out << left;
out << item.rb << '\n'
<< setw(15) << "售价:" << item.sales_price << '\n'
<< setw(15) << "销售数量:" << item.sales_amount << '\n'
<< setw(15) << "营收:" << item.get_revenue();
return out;
}task2.cpp
#include <algorithm>
#include <iomanip>
#include <iostream>
#include <string>
#include <vector>
#include "booksale.hpp"
// 按图书销售数量比较
bool compare_by_amount(const BookSale &x1, const BookSale &x2) {
return x1.get_amount() > x2.get_amount();
}
void test() {
using std::cin;
using std::cout;
using std::getline;
using std::sort;
using std::string;
using std::vector;
using std::ws;
vector<BookSale> sales_records; // 图书销售记录表
int books_number;
cout << "录入图书数量: ";
cin >> books_number;
cout << "录入图书销售记录\n";
for(int i = 0; i < books_number; ++i) {
string name, author, translator, isbn;
double price;
cout << string(20, '-') << "第" << i+1 << "本图书信息录入" << string(20, '-') << '\n';
cout << "录入书名: "; getline(cin>>ws, name);
cout << "录入作者: "; getline(cin>>ws, author);
cout << "录入译者: "; getline(cin>>ws, translator);
cout << "录入isbn: "; getline(cin>>ws, isbn);
cout << "录入定价: "; cin >> price;
Book book(name, author, translator, isbn, price);
double sales_price;
int sales_amount;
cout << "录入售价: "; cin >> sales_price;
cout << "录入销售数量: "; cin >> sales_amount;
BookSale record(book, sales_price, sales_amount);
sales_records.push_back(record);
}
// 按销售册数排序
sort(sales_records.begin(), sales_records.end(), compare_by_amount);
// 按销售册数降序输出图书销售信息
cout << string(20, '=') << "图书销售统计" << string(20, '=') << '\n';
for(auto &record: sales_records) {
cout << record << '\n';
cout << string(40, '-') << '\n';
}
}
int main() {
test();
}2、运行结果截图：
3、问题1：重载运算符<<
（1）找出运算符 << 被重载了几处？分别用于什么类型？
std::ostream& operator<<(std::ostream &out, const Book &book)
std::ostream& operator<<(std::ostream &out, const BookSale &item)
有两处，分别为Book类型，BookSale类型
（2）找出使用重载 << 输出对象的代码，写在下面。
for(auto &record: sales_records) {
cout << record << '\n';
cout << string(40, '-') << '\n';
}
4、问题2：图书销售统计task2.cpp 中定义了函数
（1）图书销售记录"按销售数量降序排序"，代码是如何实现的？
A.compare_by_amount：bool compare_by_amount(const BookSale &x1, const BookSale &x2)
{
return x1.get_amount() > x2.get_amount();
}//true:x1在x2前
B.// 按销售册数排序
sort(sales_records.begin(), sales_records.end(), compare_by_amount);
（2）拓展（选答*）：如果使用lambda表达式，如何实现"按销售数量降序排序"？
sort(sales_list.begin(), sales_list.end(),[](const BookSale &x1, const BookSale &x2) {return x1.get_amount() > x2.get_amount();});
接受两个const BookSale类型的引用作为参数，并返回一个bool值，true:x1在x2前
三、任务4
1、源代码：
pet.hpp
#pragma once
#include <string>
#include <iostream>
class MachinePet
{
public:
MachinePet(const std::string &nickname) : nickname_(nickname) {}
virtual ~MachinePet() = default;
std::string get_nickname() const
{
return nickname_;
}
virtual std::string talk() const = 0;
private:
std::string nickname_;
};//抽象基类：机器宠物
class PetCat : public MachinePet
{
public:
PetCat(const std::string &nickname) : MachinePet(nickname) {}
virtual std::string talk() const override
{
return "miao wu-";
}
};
class PetDog : public MachinePet
{
public:
PetDog(const std::string &nickname) : MachinePet(nickname) {}
virtual std::string talk() const override
{
return "wang wang~";
}
};task4.cpp
#include <iostream>
#include <memory>
#include <vector>
#include "pet.hpp"
void test1() {
std::vector<MachinePet *> pets;
pets.push_back(new PetCat("miku"));
pets.push_back(new PetDog("da huang"));
for(MachinePet *ptr: pets) {
std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n';
delete ptr;
}
}
/*
void test2() {
std::vector<std::unique_ptr<MachinePet>> pets;
pets.push_back(std::make_unique<PetCat>("miku"));
pets.push_back(std::make_unique<PetDog>("da huang"));
for(auto const &ptr: pets)
std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n';
}
*/
void test3() {
MachinePet pet("little cutie");
const PetCat cat("miku");
std::cout << cat.get_nickname() << " says " << cat.talk() << '\n';
const PetDog dog("da huang");
std::cout << dog.get_nickname() << " says " << dog.talk() << '\n';
}
int main() {
std::cout << "测试1: 使用原始指针\n";
test1();
/* std::cout << "\n测试2: 使用智能指针\n";
test2();
*/
std::cout << "\n测试3: 直接使用类籠\n";
test3();
}2、运行结果截图：
不支持智能指针，注释掉了。
四、任务5
1、源代码：
Complex.hpp
#pragma once
#include <iostream>
#include <type_traits>
template<typename T>
class Complex
{
static_assert(std::is_arithmetic<T>::value, "Complex type must be arithmetic");
private:
T real_;
T imag_;
public:
Complex() : real_(0), imag_(0) {}
Complex(T real, T imag) : real_(real), imag_(imag) {}
Complex(const Complex<T>& other) : real_(other.real_), imag_(other.imag_) {}
T get_real() const
{ return real_; }
T get_imag() const
{ return imag_; }
Complex<T>& operator+=(const Complex<T>& rhs)
{
real_ += rhs.real_;
imag_ += rhs.imag_;
return *this;
}
Complex<T> operator+(const Complex<T>& rhs) const
{
return Complex<T>(real_ + rhs.real_, imag_ + rhs.imag_);
}
bool operator==(const Complex<T>& rhs) const
{
return (real_ == rhs.real_) && (imag_ == rhs.imag_);
}
friend std::ostream& operator<<(std::ostream& os, const Complex<T>& c)
{
os << c.real_;
if (c.imag_ >= 0)
{
os << " + " << c.imag_ << "i";
}
else
{
os << " - " << -c.imag_ << "i";
}
return os;
}
friend std::istream& operator>>(std::istream& is, Complex<T>& c)
{
is >> c.real_ >> c.imag_;
return is;
}
};task5.cpp
#include <iostream>
#include "Complex.hpp"
void test1() {
using std::cout;
using std::boolalpha;
Complex<int> c1(2, -5), c2(c1);
cout << "c1 = " << c1 << '\n';
cout << "c2 = " << c2 << '\n';
cout << "c1 + c2 = " << c1 + c2 << '\n';
c1 += c2;
cout << "c1 = " << c1 << '\n';
cout << boolalpha << (c1 == c2) << '\n';
}
void test2() {
using std::cin;
using std::cout;
Complex<double> c1, c2;
cout << "Enter c1 and c2: ";
cin >> c1 >> c2;
cout << "c1 = " << c1 << '\n';
cout << "c2 = " << c2 << '\n';
const Complex<double> c3(c1);
cout << "c3.real = " << c3.get_real() << '\n';
cout << "c3.imag = " << c3.get_imag() << '\n';
}
int main() {
std::cout << "鑷畾涔夌被妯℃澘Complex娴嬭瘯1: \n";
test1();
std::cout << "\n鑷畾涔夌被妯℃澘Complex娴嬭瘯2: \n";
test2();
}2、运行结果截图：
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