复制构造函数中的深拷贝的问题

Question

我想通过复制构造函数创建我的类的实例的深层副本，但我无法弄清楚，如何编写它..在这一刻，当我调用复制构造函数，程序不会崩溃，但是当我想要对实例进行任何操作时（例如，打印数组，向其中添加一些项目等），那么程序崩溃...

有人请告诉我，如何正确写入？它的驾驶我疯狂又O_O

struct DbChange { 
    const char* date; 
    const char* street; 
    const char* city; 
}; 

class DbPerson { 
public: 
    DbPerson(void); 
    const char* id; 
    const char* name; 
    const char* surname; 
    DbChange * change; 
    int position; 
    int size; 
}; 

DbPerson::DbPerson() { 
    position = 0; 
    size = 1000; 
    change = new DbChange[1000]; 
} 

class Register { 
public: 
    // default constructor 
    Register(void); 

    int size; 
    int position; 
    DbPerson** db; 

    //copy constructor 
    Register(const Register& other) : db() {  
     db= new DbPerson*[1000];  
     std::copy(other.db, other.db + (1000), db);  
    } 
}; 


int main(int argc, char** argv) { 
    Register a; 
    /* 
    * put some items to a 
    */ 

    Register b (a); 

    a . Print(); // now crashes 
    b . Print(); // when previous line is commented, then it crashes on this line... 

    return 0; 
} 

Answer 1

由于绝不所示的代码可以让我们猜测打印呢，为什么chashes，我就告诉你我是怎么会想到事情在C++（而不是C和Java之间的尴尬的混合）：

http://liveworkspace.org/code/4ti5TS$0

#include <vector> 
#include <string> 

struct DbChange { 
    std::string date; 
    std::string street; 
    std::string city; 
}; 

class DbPerson { 
    public: 
     DbPerson(void); 

     std::string id, name, surname; 
     int position; 
     std::vector<DbChange> changes; 

     size_t size() const { return changes.size(); } 
}; 

DbPerson::DbPerson() : position(), changes() { } 

class Register { 
    public: 
     size_t size() const { return db.size(); } 
     int position; // unused? 
     std::vector<DbPerson> db; 

     Register() = default; 

     //copy constructor 
     Register(const Register& other) : db(other.db) 
     { 
      // did you forget to copy position? If so, this would have been the 
      // default generated copy constructor 
     } 

     void Print() const 
     { 
      // TODO 
     } 
}; 


int main() { 
    Register a; 
    /* 
    * put some items to a 
    */ 

    Register b(a); 

    a.Print(); // now crashes 
    b.Print(); // when previous line is commented, then it crashes on this line... 

    return 0; 
}