C++问题:定义一个Rectangle类,包括两个数据成员length和width,以及用于求长方形面积的成员函数.

#includeusing namespace std;class Rectangle{protected:double length,width;public:Rectangle(double a,double b):length(a),width(b){}double area(){return length*width;}};class Rectangular:publiv class Rectangle{double height;public:Rectangular(double a,double b,double c):Rectangle(a,b){height=c;}doouble tiji(){return length * width * height ; }};int main(){Rectangle r1(1,2);Rectangular r2(1,2,3);cout