c++ - Why can't I add pointers?

Question

I have code very similiar to this:

LINT_rep::Iterator::difference_type LINT_rep::Iterator::operator+(const Iterator& right)const
{
    return (this + &right);//IN THIS PLACE I'M GETTING AN ERROR
}

LINT_rep::Iterator::difference_type LINT_rep::Iterator::operator-(const Iterator& right)const
{//substracts one iterator from another
    return (this - &right);//HERE EVERYTHING IS FINE
}

err msg: Error  1   error C2110: '+' : cannot add two pointers

Why I'm getting an error only in one place and not in both?

Answer 1

742 Evergreen Terrace + 1 = 743 Evergreen Terrace

742 Evergreen Terrace - 1 = 741 Evergreen Terrace

743 Evergreen Terrace - 741 Evergreen Terrace = 2

743 Evergreen Terrace + 741 Evergreen Terrace = ???