有如下程序: #include using namespace std; class Boat; class Car{ public:Car(int i):weight(i){ }friend int Total(const Car &c.const Boat &b);//① private:int weight; }; class Boat{ public: Boat(int i):weight(i){ } friend int Total(const Car &c,const Boat &b); private:int weight; }; int Total(const Car &c,const Boat &b){ //②return c.weight+b.weight; } int main(){Car c(10);Boat b(8); cout<<"The total weight is"<
