赋值运算符重载

#include <iostream>

class Person
{
public:
   Person()
   {
      m_age = NULL;
   }

   Person(int age)
   {
      std::cout << "Person " << this << std::endl;

      m_age = new(int);
      age_set(age);
   }

   ~Person()
   {
      std::cout << "~Person " << this << std::endl;

      if(m_age != NULL)
      {
         delete m_age;
         m_age = NULL;
      }
   }

   Person &operator=(Person &person)
   {
      if(m_age != NULL)
      {
         delete m_age;
         m_age = NULL;
      }

      m_age = new(int);
      age_set(person.age_get());

      return *this;
   }

   int age_get()
   {
      return *m_age;
   }

   void age_set(int age)
   {
      *m_age = age;
   }

private:
   int *m_age;
};

int main()
{
   Person p1(10);
   Person p2(20);
   std::cout << p2.age_get() << std::endl;

   p2 = p1;
   std::cout << p2.age_get() << std::endl;

   return 0;
}

$ ./a.out 
Person 0x7fff66c97340
Person 0x7fff66c97350
20
10
~Person 0x7fff66c97350
~Person 0x7fff66c97340