Question

I have the following code about object sizes:

class A 
{ 
public: 
    int _i; 
    virtual int getI () = 0; 
    int setI (int i); 
}; 
class B : public A 
{ 
public: 
    int getI (); 
    virtual int setI (int i); 
}; 

class C : public B 
{ 
public: 
    int _i; 
    int getI (); 
    int setI (int i); 
}; 

int main () 
{ 
    B b; 
    C c; 
} 

Why the size of
C c;
is 12? What parts included in the size calculation?

Answer 1

sizeof(int A::_i) + sizeof(int C::_i) + sizeof(pointer to virtual table)

The size of all these parts is implementation-dependent, in your case, each one has size 4.