Constructor - deep and shallow copy copy

. 1 #include <the iostream>
 2 #include < String >
 . 3  the using  namespace STD;
 . 4  // constructor (copy constructor), destructor, 
5  / * deep copy: refers to the class provides the compiler given a default copy constructor when the copy contains member objects,
 6           call the default heap destructor releases the same memory repeatedly, leading to a memory access exception.
7  
8  The solution: a custom copy constructor for a pointer member,
 9           to open up another piece of heap memory with the new keyword, stored pointer member copy of the object.
10  * / 
. 11  class Student
 12 is  {
 13 is  public :
 14  
15      Student ()} {
 16      // Default destructor 
17      / * 
18     Student( Student &stu)
19     {
20         m_age = stu.m_age;
21         p = stu.p;
22     }
23     */
24 
25     //自定义析构函数
26     Student(const Student &stu)
27     {
28         m_age = stu.m_age;
29         p = new int(*stu.p);
30     }
31 
32     void showStudent()
33     {
34         cout << m_age << endl;;
35         * P << << COUT endl;
 36          COUT << "" << endl;
 37 [      }
 38 is  // Private: 
39      int m_age;
 40      int * P;
 41 is  
42 is  };
 43 is  
44 is  int main ()
 45  {
 46 is      int A = . 6 ;
 47      // Student S1 (10, & A) an erroneous operation, since the destructor defined, the compiler will not provide a default constructor to initialize general; 
48      Student S1;
 49      s1.m_age = 10 ;
 50      s1.p & A = ;
 51 is 
52 is      Student S2 = S1;
 53 is      s1.showStudent ();
 54 is      s2.showStudent ();
 55  
56 is      System ( " PAUSE " );
 57 is      return  0 ;
 . 5 // Constructor