Is this valid C++ (protected member of base accessed in derived class function)

[Shelly Adhikari]

class B {
public:
B() { }
~B() { }
protected:
int abc;
void g() {}
};

class C : public B {
public:
void f(B* p) {
p->g(); // Should this be an error?
int m = p->abc; // Should this be an error?
int n = abc;
g();
}
};

int main() {
B* y = new B();
C x;
x.f(y);
}

If you could also point me to the ISO C++ standard section and page
number, it would be great.

 

[=?iso-8859-1?Q?Juli=E1n?= Albo]

Shelly Adhikari escribió:

class B {
public:
B() { }
~B() { }
protected:
int abc;
void g() {}
};

class C : public B {
public:
void f(B* p) {
p->g(); // Should this be an error?
int m = p->abc; // Should this be an error?

Yes, they are errors. You have access only to a the B that is part of a
C, not to a unrelated B.

Regards.

 

[Ron Natalie]

p->g(); // Should this be an error?
int m = p->abc; // Should this be an error? Yes, these are both errors.
int n = abc;
g();

These are OK.

Protected only lets you get at your own instances (this's) subobjects.

 

[red floyd]

[protected member access question redacted]

To whoever maintains the FAQs:

Is this one in the FAQs? It's been asked at least five times in the past week. If it isn't,
it should be in there.