CODEWITHSUNDEEP
c++
ManuelSchneid3r
ManuelSchneid3r

Reputation: 16091

Does an instantiation of a derived class allocate memory for private members of base class?

I guess the topic is all I need to ask. A little explanation around the topic would be nice. Please clear some questions like why or why not?

Example:

class A {
 private:
  int a;
};

class B : A {
 int b;
};

int main (int argc, char **argv) {
 B *p = new B(); // Does this allocate memory for a?
}

Upvotes: 3

Views: 767

Answers (3)

Dietmar Kühl
Dietmar Kühl

Reputation: 153830

It depends on what you mean with allocate: it does not do a heap allocation or something. A derived object will contain the members inherited from the base. That is all base classes of a derived class can be seen as subobjects. The derived class objects will contain all these subobjects and will also make sure that they are properly constructed/destructed.

Upvotes: 2

Arun Sharma
Arun Sharma

Reputation: 517

Yes it will allocate memory for A also.

Because when you inherit a class from another class and when you create the object of derived class, Complier will allocate memory equal to size of derived class+base class,so that there would be no loss of data. As base class members are also accessible from derived class.

Upvotes: 1

Mike Seymour
Mike Seymour

Reputation: 254461

Yes. A class object contains all of its direct non-static data members, and those of any base-class sub-objects. Access specifiers make no difference; they merely restrict where names can be used.

Upvotes: 6

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