继承与派生

  定义一个point类，派生Rectangle类和Circle类，计算各派生类对象的面积Area().

#include<iostream> 
using namespace std;
class point
{
    protected:
        double x;
        double y;
        public:
            point(double X,double Y):x(X),y(Y)
            {            }
            double getX() const
            {
                 return x;              
            }
            double getY() const
            {
                return y; 
            }    
};
class Rectangle:public point 
{
        protected:
        double longth;
        double width;
        public:
            Rectangle(double X,double Y,double l,double w):point(X,Y),longth(l),width(w){
            }
            double getArea() const
            {
                return longth*width;
            }
};
class Circle:public point
{
    protected:
        double r;
        public:
            Circle(double X,double Y,double R):point(X,Y),r(R){
            }
            double getArea() const
            {
                return (3.14159*r*r);
            }        
};
int main()
{Rectangle A(0,0,5,2);
Circle B(0,0,2);
cout<<"Rectangle area"<<A.getArea()<<endl;
cout<<"Circle area"<<B.getArea()<<endl;
return 0;

设计一个建筑物类Building，由它派生出教学楼TeachBuilding和宿舍楼类DormBuilding，前者包括教学楼编号，层数，教室数，总面积等基本信息，后者包括宿舍楼编号，层数，宿舍数，总面积和容纳学生总人数等基本信息。

 1 #include<iostream>
 2 using namespace std;
 3 class Building
 4 {
 5     protected:
 6         int number;
 7         int floor;
 8         double area;
 9         public:
10             Building(int N,int F,double A):number(N),floor(F),area(A){                
11             }
12             int getnumber() const{
13             return number;}
14             int getfloor() const{
15             return floor;}
16             double getarea() const{
17             return area;}
18 };
19 class TeachBuilding:public Building{
20     private:
21         int classroom;
22         public:
23         TeachBuilding(int N,int F,double A,int R):Building(N,F,A),classroom(R){
24 
25         }
26         int grtclassroom() const{
27         return classroom;}    
28 };
29 class DormBuilding:public Building{
30     private:
31     int dorm;
32     int student;
33     public:
34       DormBuilding(int N,int F,double A,int D,int S):Building(N,F,A),dorm(D),student(S){
35       }
36       int getdorm() const{
37       return  dorm;}
38       int getstudent()const{
39       return student;}
40 };
41 int main()
42 {
43     TeachBuilding O(1,4,34,600);
44     DormBuilding E(2,5,23,400,64);
45     cout<<"TeachBuilding number="<<O.getnumber()<<" floor="<<O.getfloor()<<" classroom="<<O.grtclassroom()<<" area="<<O.getarea()<<endl;
46     cout<<"DormBuilding number="<<E.getnumber()<<" floor="<<E.getfloor()<<" dorm="<<E.getdorm()<<" area="<<E.getarea()<<" student="<<E.getstudent()<<endl;
47     return 0;
48 }