C++ Primer Plus

Returning an Object

If the object being returned is local to the called function, then it should not be returned by reference because the local object has its destructor called when the function terminates. Thus, when control returns to the calling function, there is no object left to which the reference can refer. In these circumstances, you should return an object, not a reference. Typically, overloaded arithmetic operators fall into this category. Consider this example, which uses the Vector class again:

Vector force1(50,60);Vector force2(10,70);Vector net;net = force1 + force2;

The value being returned is not force1, which should be left unaltered by the process, nor force2, which should also be unaltered. Thus the return value can’t be a ...