struct和class and inheritance（c ++）

Question

Could you ensure me, if all access specifiers (including inheritance) in struct are public ?

In other words: are those equal?

class C: public B, public A { public:
    C():A(1),B(2){}
    //...
};

and

struct C: B, A {
    C():A(1),B(2){}
    //...
};

Answer 1

Yes, they all are public.

struct A : B {
  C c;
  void foo() const {}
}

is equivalent to

struct A : public B {
 public:
  C c;
  void foo() const {}
}

For members, it is specified in §11:

Members of a class defined with the keyword class are private by default. Members of a class defined with the keywords struct or union are public by default.

and for for base classes in §11.2:

In the absence of an access-specifier for a base class, public is assumed when the derived class is defined with the class-key struct and private is assumed when the class is defined with the class-key class.

where the references are to the C++11 standard.

Answer 2

From C++ standard , 11.2.2, page 208:

In the absence of an access-specifier for a base class, public is assumed when the derived class is declared struct and private is assumed when the class is declared class.

So yes, you are correct: when the derived class is a struct , it inherits other classes as public unless you specify otherwise.

Answer 3

From the C++11 Standard ( N3242 draft )

11.2 Accessibility of base classes and base class members

2 In the absence of an access-specifier for a base class, public is assumed when the derived class is defined with the class-key struct and private is assumed when the class is defined with the class-key class.