class bigbox : public box {public: bigbox (int i, double d) : box(i), dvalue(d) { } void operator = (bigbox & right) { value = right.value; dvalue = right.dvalue; }protected: double dvalue;
class bigbox : public box {public: bigbox (int i, double d) : box(i), dvalue(d) { } void operator = (bigbox & right) { value = right.value; dvalue = right.dvalue; }protected: double dvalue;
a = b; // legal, but sliced, box assignment,
b = a; // not legal, argument must be a bigbox