Returning an address to a local variable vs returning a pointer to a local variable

Question

I have this in my testing.cpp:

class Supp{
public:
virtual Supp* add(Supp& val) = 0;
};

class SubA : public Supp{
public:
int val;

SubA(int a){
    val = a         


        

Answer 1

Initially misread the question, sorry.

The second works because you're not returning by reference, but by value. If the signature was

Supp*& add(Supp& value)

then the second would be illegal as well.

Keep in mind that objects with automatic storage duration get destroyed at the closing }. So after the functions return, the object b is no longer accessible. Copies of it are. If you return by value, the original goes away, but you're left with the copy.