C++ Operator Overload Returns contents of the this pointer

#include <iostream>
using namespace std;
class alpha/*from  w  ww  .j  a va  2s .  co  m*/
{
   private:
   int data;
   public:
   alpha()                      //no-arg constructor
   { }
   alpha(int d)                 //one-arg constructor
   { data = d; }
   void display()               //display data
   { cout << data; }
   alpha& operator = (alpha& a) //overloaded = operator
   {
      data = a.data;            //not done automatically
      cout << "\nAssignment operator invoked";
      return *this;             //return copy of this alpha
   }
};
int main()
{
   alpha a1(37);
   alpha a2, a3;
   a3 = a2 = a1;                   //invoke overloaded =, twice
   cout << "\na2="; a2.display();  //display a2
   cout << "\na3="; a3.display();  //display a3
   cout << endl;
   return 0;
}