Is there a fundamental different between the copy constructor and the assignment operator?
Yes, there is. Although the copy constructor and the assignment operator have similar functions, they differ in one crucial aspect. A copy construction operation is a constructor call by all means. That is, the object being constructed during a copy constructor invocation has an indeterminate state until the copy constructor has returned successfully. Furthermore, a copy constructor doesn’t return any value (not even void) — very much like any other constructor whereas an assignment operator has a return value. A copy constructor will be called only when a new object is being instantiated. The assignment operator is called for an existing object to which a new value is being assigned.
