Assigning an object to itself is disastrous, so whenever you have to define a copy constructor and assignment operator, make sure your code is guarded from such a mistake:

 class Date {	int day, month, year;	//...	Date & operator= (const Date & other){ *this=other; //Dangerous 								return *this;}	//...}void f () {	Date d;	Date *pdate = &d;	//...many lines of code 	*pdate=d; //oops, object assigned to itself; disastrous}//f()

A safe version should look like this:

 Date & Date::operator= (const Date & other) { 	if (&other != this) //guarded from self assignment	{		*this = other;		//...	}	return *this; }