實驗任務1：
代碼：
publisher.cpp
1 #include <iostream> 2 #include <string> 3 #include "publisher.hpp" 4 5 Publisher::Publisher(const std::string &name_): name {name_} { 6 } 7 8 9 Book::Book(const std::string &name_ , const std::string &author_ ): Publisher{name_}, author{author_} { 10 } 11 12 void Book::publish() const { 13 std::cout << "Publishing book《" << name << "》 by " << author << '\n'; 14 } 15 16 void Book::use() const { 17 std::cout << "Reading book 《" << name << "》 by " << author << '\n'; 18 } 19 20 21 Film::Film(const std::string &name_, const std::string &director_):Publisher{name_},director{director_} { 22 } 23 24 void Film::publish() const { 25 std::cout << "Publishing film <" << name << "> directed by " << director << '\n'; 26 } 27 28 void Film::use() const { 29 std::cout << "Watching film <" << name << "> directed by " << director << '\n'; 30 } 31 32 33 Music::Music(const std::string &name_, const std::string &artist_): Publisher{name_}, artist{artist_} { 34 } 35 36 void Music::publish() const { 37 std::cout << "Publishing music <" << name << "> by " << artist << '\n'; 38 } 39 40 void Music::use() const { 41 std::cout << "Listening to music <" << name << "> by " << artist << '\n'; 42 }
publisher.hpp
1 #pragma once 2 3 #include <string> 4 5 class Publisher { 6 public: 7 Publisher(const std::string &name_ = ""); 8 virtual ~Publisher() = default; 9 10 public: 11 virtual void publish() const = 0; // 純虛函數，作為接口繼承 12 virtual void use() const = 0; // 純虛函數，作為接口繼承 13 14 protected: 15 std::string name; // 發行/出版物名稱 16 }; 17 18 // 圖書類: Book 19 class Book: public Publisher { 20 public: 21 Book(const std::string &name_ = "", const std::string &author_ = ""); // 構造函數 22 23 public: 24 void publish() const override; // 接口 25 void use() const override; // 接口 26 27 private: 28 std::string author; // 作者 29 }; 30 31 // 電影類: Film 32 class Film: public Publisher { 33 public: 34 Film(const std::string &name_ = "", const std::string &director_ = ""); // 構造函數 35 36 public: 37 void publish() const override; // 接口 38 void use() const override; // 接口 39 40 private: 41 std::string director; // 導演 42 }; 43 44 45 // 音樂類：Music 46 class Music: public Publisher { 47 public: 48 Music(const std::string &name_ = "", const std::string &artist_ = ""); 49 50 public: 51 void publish() const override; // 接口 52 void use() const override; // 接口 53 54 private: 55 std::string artist; // 音樂藝術家名稱 56 };
task1.cpp
1 #include <memory> 2 #include <iostream> 3 #include <vector> 4 #include "publisher.hpp" 5 6 void test1() { 7 std::vector<Publisher *> v; 8 9 v.push_back(new Book("Harry Potter", "J.K. Rowling")); 10 v.push_back(new Film("The Godfather", "Francis Ford Coppola")); 11 v.push_back(new Music("Blowing in the wind", "Bob Dylan")); 12 13 for(Publisher *ptr: v) { 14 ptr->publish(); 15 ptr->use(); 16 std::cout << '\n'; 17 delete ptr; 18 } 19 } 20 21 void test2() { 22 std::vector<std::unique_ptr<Publisher>> v; 23 24 v.push_back(std::make_unique<Book>("Harry Potter", "J.K. Rowling")); 25 v.push_back(std::make_unique<Film>("The Godfather", "Francis Ford Coppola")); 26 v.push_back(std::make_unique<Music>("Blowing in the wind", "Bob Dylan")); 27 28 for(const auto &ptr: v) { 29 ptr->publish(); 30 ptr->use(); 31 std::cout << '\n'; 32 } 33 } 34 35 void test3() { 36 Book book("A Philosophy of Software Design", "John Ousterhout"); 37 book.publish(); 38 book.use(); 39 } 40 41 int main() { 42 std::cout << "運行時多態：純虛函數、抽象類\n"; 43 44 std::cout << "\n測試1: 使用原始指針\n"; 45 test1(); 46 47 std::cout << "\n測試2: 使用智能指針\n"; 48 test2(); 49 50 std::cout << "\n測試3: 直接使用類\n"; 51 test3(); 52 }
運行測試截圖：
回答問題：
問題1：
（1）Publisher類中包含純虛函數。具體依據：virtual void publish() const = 0;和virtual void use() const = 0；
（2）不能編譯通過。因為抽象類不能實例化對象。
問題2：
（1）void publish() const override;
void use() const override;
（2）函數簽名與基類不匹配，無法重寫
問題3：
（1）ptr的聲明類型是Publisher*
（2）Book, Film, Music
（3）原因：實現多態析構，確保刪除派生類對象時，先調用派生類析構函數，再調用基類析構函數，避免內存泄漏；若刪除virtual,派生類的析構函數不被調用，內存泄漏。
實驗任務2：
代碼：
book.hpp
1 #pragma once 2 #include <string> 3 4 // 圖書描述信息類Book: 聲明 5 class Book { 6 public: 7 Book(const std::string &name_, 8 const std::string &author_, 9 const std::string &translator_, 10 const std::string &isbn_, 11 double price_); 12 13 friend std::ostream& operator<<(std::ostream &out, const Book &book); 14 15 private: 16 std::string name; // 書名 17 std::string author; // 作者 18 std::string translator; // 譯者 19 std::string isbn; // isbn號 20 double price; // 定價 21 };
book.cpp
1 #include <iomanip> 2 #include <iostream> 3 #include <string> 4 #include "book.hpp" 5 6 7 // 圖書描述信息類Book: 實現 8 Book::Book(const std::string &name_, 9 const std::string &author_, 10 const std::string &translator_, 11 const std::string &isbn_, 12 double price_):name{name_}, author{author_}, translator{translator_}, isbn{isbn_}, price{price_} { 13 } 14 15 // 運算符<<重載實現 16 std::ostream& operator<<(std::ostream &out, const Book &book) { 17 using std::left; 18 using std::setw; 19 20 out << left; 21 out << setw(15) << "書名:" << book.name << '\n' 22 << setw(15) << "作者:" << book.author << '\n' 23 << setw(15) << "譯者:" << book.translator << '\n' 24 << setw(15) << "ISBN:" << book.isbn << '\n' 25 << setw(15) << "定價:" << book.price; 26 27 return out; 28 }
booksale.hpp
1 #pragma once 2 3 #include <string> 4 #include "book.hpp" 5 6 // 圖書銷售記錄類BookSales：聲明 7 class BookSale { 8 public: 9 BookSale(const Book &rb_, double sales_price_, int sales_amount_); 10 int get_amount() const; // 返回銷售數量 11 double get_revenue() const; // 返回營收 12 13 friend std::ostream& operator<<(std::ostream &out, const BookSale &item); 14 15 private: 16 Book rb; 17 double sales_price; // 售價 18 int sales_amount; // 銷售數量 19 };
booksale.cpp
1 #include <iomanip> 2 #include <iostream> 3 #include <string> 4 #include "booksale.hpp" 5 6 // 圖書銷售記錄類BookSales：實現 7 BookSale::BookSale(const Book &rb_, 8 double sales_price_, 9 int sales_amount_): rb{rb_}, sales_price{sales_price_}, sales_amount{sales_amount_} { 10 } 11 12 int BookSale::get_amount() const { 13 return sales_amount; 14 } 15 16 double BookSale::get_revenue() const { 17 return sales_amount * sales_price; 18 } 19 20 // 運算符<<重載實現 21 std::ostream& operator<<(std::ostream &out, const BookSale &item) { 22 using std::left; 23 using std::setw; 24 25 out << left; 26 out << item.rb << '\n' 27 << setw(15) << "售價:" << item.sales_price << '\n' 28 << setw(15) << "銷售數量:" << item.sales_amount << '\n' 29 << setw(15) << "營收:" << item.get_revenue(); 30 31 return out; 32 }
task2.cpp
1 #include <algorithm> 2 #include <iomanip> 3 #include <iostream> 4 #include <string> 5 #include <vector> 6 #include "booksale.hpp" 7 8 // 按圖書銷售數量比較 9 bool compare_by_amount(const BookSale &x1, const BookSale &x2) { 10 return x1.get_amount() > x2.get_amount(); 11 } 12 13 void test() { 14 using std::cin; 15 using std::cout; 16 using std::getline; 17 using std::sort; 18 using std::string; 19 using std::vector; 20 using std::ws; 21 22 vector<BookSale> sales_records; // 圖書銷售記錄表 23 24 int books_number; 25 cout << "錄入圖書數量: "; 26 cin >> books_number; 27 28 cout << "錄入圖書銷售記錄\n"; 29 for(int i = 0; i < books_number; ++i) { 30 string name, author, translator, isbn; 31 double price; 32 cout << string(20, '-') << "第" << i+1 << "本圖書信息錄入" << string(20, '-') << '\n'; 33 cout << "錄入書名: "; getline(cin>>ws, name); 34 cout << "錄入作者: "; getline(cin>>ws, author); 35 cout << "錄入譯者: "; getline(cin>>ws, translator); 36 cout << "錄入isbn: "; getline(cin>>ws, isbn); 37 cout << "錄入定價: "; cin >> price; 38 39 Book book(name, author, translator, isbn, price); 40 41 double sales_price; 42 int sales_amount; 43 44 cout << "錄入售價: "; cin >> sales_price; 45 cout << "錄入銷售數量: "; cin >> sales_amount; 46 47 BookSale record(book, sales_price, sales_amount); 48 sales_records.push_back(record); 49 } 50 51 // 按銷售冊數排序 52 sort(sales_records.begin(), sales_records.end(), compare_by_amount); 53 54 // 按銷售冊數降序輸出圖書銷售信息 55 cout << string(20, '=') << "圖書銷售統計" << string(20, '=') << '\n'; 56 for(auto &record: sales_records) { 57 cout << record << '\n'; 58 cout << string(40, '-') << '\n'; 59 } 60 } 61 62 int main() { 63 test(); 64 }
運行測試截圖：
回答問題：
問題1：
（1）兩處。Book類型和BookSale類型
（2）book.cpp中：std::ostream& operator<<(std::ostream &out, const Book &book);
booksale.cpp中：std::ostream& operator<<(std::ostream &out, const BookSale &item);
task2.cpp中：cout << t <<endl;
問題2：
（1）使用 std::sort 函數，配合自定義比較函數 compare_by_amount
實驗任務4：
pet.hpp
1 #pragma once 2 #include <string> 3 4 class MachinePet { 5 public: 6 MachinePet(const std::string& nickname_) : nickname(nickname_) {} 7 virtual ~MachinePet() = default; 8 9 std::string get_nickname() const { 10 return nickname; 11 } 12 13 virtual std::string talk() const = 0; 14 15 protected: 16 std::string nickname; 17 }; 18 19 class PetCat : public MachinePet { 20 public: 21 PetCat(const std::string& nickname_) : MachinePet(nickname_) {} 22 23 std::string talk() const override { 24 return "miao wu~"; 25 } 26 }; 27 28 class PetDog : public MachinePet { 29 public: 30 PetDog(const std::string& nickname_) : MachinePet(nickname_) {} 31 32 std::string talk() const override { 33 return "wang wang~"; 34 } 35 };
task4.cpp
1 #include <iostream> 2 #include <memory> 3 #include <vector> 4 #include "pet.hpp" 5 6 void test1() { 7 std::vector<MachinePet *> pets; 8 9 pets.push_back(new PetCat("miku")); 10 pets.push_back(new PetDog("da huang")); 11 12 for(MachinePet *ptr: pets) { 13 std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n'; 14 delete ptr; // 須手動釋放資源 15 } 16 } 17 18 void test2() { 19 std::vector<std::unique_ptr<MachinePet>> pets; 20 21 pets.push_back(std::make_unique<PetCat>("miku")); 22 pets.push_back(std::make_unique<PetDog>("da huang")); 23 24 for(auto const &ptr: pets) 25 std::cout << ptr->get_nickname() << " says " << ptr->talk() << '\n'; 26 } 27 28 void test3() { 29 // MachinePet pet("little cutie"); // 編譯報錯：無法定義抽象類對象 30 31 const PetCat cat("miku"); 32 std::cout << cat.get_nickname() << " says " << cat.talk() << '\n'; 33 34 const PetDog dog("da huang"); 35 std::cout << dog.get_nickname() << " says " << dog.talk() << '\n'; 36 } 37 38 int main() { 39 std::cout << "測試1: 使用原始指針\n"; 40 test1(); 41 42 std::cout << "\n測試2: 使用智能指針\n"; 43 test2(); 44 45 std::cout << "\n測試3: 直接使用類\n"; 46 test3(); 47 }
運行測試截圖：
實驗任務5：
Complex.hpp
1 #pragma once 2 #include <iostream> 3 4 template<typename T> 5 class Complex { 6 private: 7 T real; 8 T imag; 9 10 public: 11 Complex() : real(0), imag(0) {} 12 Complex(T real_, T imag_) : real(real_), imag(imag_) {} 13 Complex(const Complex &other) : real(other.real), imag(other.imag) {} 14 15 T get_real() const { return real; } 16 T get_imag() const { return imag; } 17 18 Complex &operator+=(const Complex &other) { 19 real += other.real; 20 imag += other.imag; 21 return *this; 22 } 23 24 friend Complex operator+(const Complex &c1, const Complex &c2) { 25 Complex temp = c1; 26 temp += c2; 27 return temp; 28 } 29 30 friend bool operator==(const Complex &c1, const Complex &c2) { 31 return c1.real == c2.real && c1.imag == c2.imag; 32 } 33 34 friend std::ostream &operator<<(std::ostream &out, const Complex &c) { 35 out << c.real; 36 if (c.imag >= 0) { 37 out << "+" << c.imag << "i"; 38 } else { 39 out << c.imag << "i"; 40 } 41 return out; 42 } 43 44 friend std::istream &operator>>(std::istream &in, Complex &c) { 45 in >> c.real >> c.imag; 46 return in; 47 } 48 49 };
task5.cpp
1 #include <iostream> 2 #include "Complex.hpp" 3 4 void test1() { 5 using std::cout; 6 using std::boolalpha; 7 8 Complex<int> c1(2, -5), c2(c1); 9 10 cout << "c1 = " << c1 << '\n'; 11 cout << "c2 = " << c2 << '\n'; 12 cout << "c1 + c2 = " << c1 + c2 << '\n'; 13 14 c1 += c2; 15 cout << "c1 = " << c1 << '\n'; 16 cout << boolalpha << (c1 == c2) << '\n'; 17 } 18 19 void test2() { 20 using std::cin; 21 using std::cout; 22 23 Complex<double> c1, c2; 24 cout << "Enter c1 and c2: "; 25 cin >> c1 >> c2; 26 cout << "c1 = " << c1 << '\n'; 27 cout << "c2 = " << c2 << '\n'; 28 29 const Complex<double> c3(c1); 30 cout << "c3.real = " << c3.get_real() << '\n'; 31 cout << "c3.imag = " << c3.get_imag() << '\n'; 32 } 33 34 int main() { 35 std::cout << "自定義類模板Complex測試1: \n"; 36 test1(); 37 38 std::cout << "\n自定義類模板Complex測試2: \n"; 39 test2(); 40 }
運行測試截圖：
