Move constructor and assignment operator in C++

In addition to copy constructor and assignment operator C++ got so-called move constructor and assignment operator. First I am gonna show you what copy constructor and assignment operators are:

class A
{
public:
    int* some_data;

    A()
    {
        some_data = new int[128];
    }

   // Copy constructor
   A(const A& a)
   {
        some_data = new int[128];
        memcpy(some_data, a.some_data, 128);
   }

    ~A()
    {
        delete[] some_data;
    }

// Assignment operator
    A& operator = (const A& a)
    {
        if (this != &a)
       {
            delete[] some_data;
            some_data = new int[128];
            memcpy(some_data, a.some_data, 128);
       }
       return *this;
    }
};

int main()
{
A a1;
A a2(a1); // Copy constructor call
A a3;
a3 = a1; // Assignment operator call

return 0;
}

As you can see both copy constructor and assignment operator do exactly the same thing, they create a copy of other instance of the same class. In the example above, copying maybe slightly optimized using move constructor and move assignment operator:

class A
{
public:
  int* some_data;

    A()
   {
        some_data = new int[128];
   }

    // Move constructor
    A(A&& a)
   {
        some_data = a.some_data;
        a.some_data = nullptr;
}

~A()
  {
delete[] some_data;
}

  // Move assignment operator
A& operator = (A&& a)
 {
if (this != &a)
{
          delete[] some_data;
          some_data = a.some_data;
          a.some_data = nullptr;
}

return *this;
  }
};

int main()
{
A a1;
A a2(std::move(a1)); // Move constructor call
A a3;
a3 = std::move(a1); // Move assignment operator call

return 0;
}

In other words, move constructor and move assignment operator are merely optimized versions of regular copy constructor and assignment operator.