How actually is a derived class implementation on inheritance ?

How actually is a derived class implementation on inheritance, as class is just abstract.
E.g.

Code:

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class A {public: int x;};
class B : public A {int y;};

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Does a B object instantly "realize" having A member.

Code:

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int main()    {

A a;
B b;
a.x =7;
b.x += 3;  // How is inheritance supposed to be?
                // how will be b.x =10?

}

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B derives public-ly from A. That roughly saying "B is of type A" AND "B has its own set of properties that may differ from A". Why don't you run the code yourself and check if b.x is 10? Is it 10 though? Try it :) Just add this to your code tho (so that you don't have uninitialised value usage):

Code:

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class A {public: int x = 0;};
class B : public A {int y = 0;};

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