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Program Out Put Does Not Make Sense!

Rave (79)
I try to test what the output of this program would be, but it doesn't make any sense,

Code:
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#include <iostream>

using namespace std;



//Why the op= is invoked twice

class A {



public:

        A()

        {

            cout<<"A ctor"<<endl;

        }

        A(const A &a)

        {

            cout <<"A copy ctor"<<endl;

        }

        ~A()

        {

            cout<<"A dtor"<<endl;

        }

        virtual void foo()

        {

            cout<<"A foo()"<<endl;

        }

        virtual A& operator=(const A &rhs)

        {

            cout<<"A op="<<endl;

        }

};



class B:public A

{

    public:

            B():A()

            {

                cout<<"B ctor"<<endl;

            }

            ~B()

            {

                cout<<"B dtor"<<endl;

            }

            virtual void foo()

            {

                cout <<"B foo()"<<endl;

            }

            protected:

            A myIstanceOfA;



};







A foo (A &input)

{

    input.foo();

    return input;

}





int main()

{

    B myB;

    B myOtherB;

    A myA;

    myOtherB=myB;

    myA=foo(myOtherB);

}








A ctor

A ctor

B ctor

A ctor

A ctor

B ctor

A ctor

A op=

A op= // WHY IS OP= EVOKED TWICE, IT SHOULD BE ONLY ONCE.

B foo()

A copy ctor

A op=

A dtor

A dtor

B dtor

A dtor

A dtor

B dtor

A dtor

A dtor

The op= or overloaded operator equal is evoked twice, where it should have only be once, any idea on what went wrong.
ERanz21 (61)
I remember seeing a program like this, but I think what's happening is that you're inheriting class A in your class B, so when you do it for class B it's gonna see everything that is pubilc in A, which in this case is everything. So it's inheriting the op part, which might cause it to print twice...

Note:
this is just a guess, so don't quote me on this, lol. I most likely am off in my reasoning.
firedraco (6243)
Your B class inherits from your A class, which means in calls A's =. Since you also didn't define an = for B, the compiler will make one for you, which means it also calls the = on the A member in your B class.
Rave (79)
ah, so the default op= in B will call op= in A, am i correct?
Rave (79)
actually its incorrect, the op= is envoked twice, for one = since there is a base class member in the derived class(the protected one)
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