析构函数 p157-白红宇

析构函数 p157

阅读量：5157 次

发布时间：2019-06-13

本文共 2044 字，大约阅读时间需要 6 分钟。

析构函数

确保对象的各部分被正确的清除，及做一些用户指定的其他清理工作。

当对象超出它的作用域时，编译器将自动调用析构函数；手动用new在堆上分配的对象空间，需要调用'delete 对象地址'进行手动清除， delete 语句先调用该对象的析构函数，然后释放内存

1 #include 
     
       2 #include 
      
        3  4 using namespace std; 5  6  7 class Publisher 8 { 9     string name;10     string address;11     string telephone;12 13 public:14     15     Publisher(string name, string address, string telephone) : name(name), address(address), telephone(telephone) 16     {17         cout << "Publisher(string name, string address, string telephone)" << endl;18     }19 20     ~Publisher()21     {22         cout << "~Publisher()" << endl;23     }24 25     friend ostream& operator<<(ostream& os, const Publisher& p)26     {27         return os << "PublisherName: " << p.name << ", PublisherAddress: " << p.address << ", Publishertelephone: " << p.telephone;28     }29 30 };31 32 33 class Book34 {35     string name;36     string author;37     double price;38     Publisher* publisher;39 40 public:41 42     Book(string name, string author, double price, Publisher* pub) : name(name), author(author), price(price), publisher(pub)43     {44         cout << "Book(string name, string author, double price, Publisher publisher)" << endl;45     }46 47     ~Book()48     {49         cout << "~Book()" << endl;50         if (publisher != 0)51         {52             delete publisher;53             publisher = 0;54             cout << "delete publisher" << endl;55         }    56     57     }58 59     friend ostream& operator<<(ostream& os, const Book& b)60     {61          os << "-------- print Book ---------------" << endl;62          os << "BookName: " << b.name << ", BookAuthor: " << b.author << ", BookPrice: " << b.price << endl;;63          os << *b.publisher << endl;;64          return os;65     }66 67 };68 69 int main()70 {71     72     Publisher* pub = new Publisher("人民出版社", "北京市西城区", "021-2134343545");73 74     Book b1("算法精解", "Kyle Loudon", 56.2, pub);75 76     cout << b1 << endl;77 78 };

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