下面的实例是使用继承完成点、圆、圆柱体的层次结构
1 #include <iostream> 2 using namespace std; 3 #define PI 3.1415926 4 5 class Point 6 { 7 friend ostream& operator << (ostream& output,Point&); 8 public: 9 Point(int x =0,int y =0); //带默认参数的构造函数 10 void setPoint(int x,int y); //设置点坐标 11 int getX(); //得到点的x轴坐标 12 int getY(); //得到点的y轴坐标 13 protected: //成员函数，x，y轴的坐标 14 int x,y; 15 }; 16 17 class Circle: public Point //类Circle公有继承Point 18 { 19 friend ostream& operator << (ostream& output,Circle&); 20 public: 21 Circle(double r = 0.0,int x =0,int y =0); //带默认参数的构造函数 22 void setRadius(double r); //设置圆的半径 23 double getRadius(); //得到圆的半径 24 double getArea(); //得到圆的面积 25 protected: 26 double radius; //成员函数，半径 27 }; 28 29 class Cylinder:public Circle //类Cylinder继承Circle 30 { 31 friend ostream& operator <<(ostream& output,Cylinder&); 32 public: 33 Cylinder(double height=0.0,double radius =0.0,int x=0,int y=0); //带默认参数的构造函数 34 void setHeight(double height); //设置圆柱体高度值 35 double getHeight(); //返回圆柱体的高度值 36 double getArea(); //返回圆柱体的面积 37 double getVolume(); //返回圆柱体的体积 38 protected: 39 double height; //成员函数，圆柱体的高度 40 }; 41 42 //Point类的实现 43 Point::Point(int x,int y) 44 { 45 this->x = x; 46 this->y = y; 47 } 48 void Point::setPoint(int x,int y) 49 { 50 this->x = x; 51 this->y = y; 52 } 53 int Point::getX() 54 { 55 return this->x; 56 } 57 int Point::getY() 58 { 59 return this->y; 60 } 61 ostream& operator <<(ostream& output,Point& point) 62 { 63 cout << "[point: x="<<point.getX()<<" ,"<<"y="<<point.getY() << "]" <<endl; 64 return output; 65 } 66 67 //Circle类的实现 68 Circle::Circle(double radius,int x,int y):Point(x,y) 69 { 70 this->radius = radius; 71 } 72 void Circle::setRadius(double radius) 73 { 74 this->radius = radius; 75 } 76 double Circle::getRadius() 77 { 78 return this->radius; 79 } 80 double Circle::getArea() 81 { 82 return PI * radius * radius; 83 } 84 ostream& operator <<(ostream& output,Circle& circle) 85 { 86 cout << "[circle: x=" << circle.getX() << " ,y=" <<circle.getY() <<" ,radius=" << circle.getRadius() << " ,area=" <<circle.getArea() << "]"<<endl; 87 return output; 88 } 89 90 //类Cylinder的实现 91 Cylinder::Cylinder(double height,double radius,int x,int y):Circle(radius,x,y) 92 { 93 this->height = height; 94 } 95 96 void Cylinder::setHeight(double height) 97 { 98 this->height = height; 99 } 100 double Cylinder::getHeight() 101 { 102 return this->height; 103 } 104 double Cylinder::getArea() 105 { 106 return 2*Circle::getArea()+2 * PI * radius * height; 107 } 108 double Cylinder::getVolume() 109 { 110 return Circle::getArea()*height; 111 } 112 ostream& operator <<(ostream& output,Cylinder& cylinder) 113 { 114 cout << "[cylinder: x=" << cylinder.getX() << " ,y=" <<cylinder.getY() << " ,height=" << cylinder.getHeight() <<" ,radius=" << cylinder.getRadius() << " ,area=" <<cylinder.getArea() <<" ,volume=" << cylinder.getVolume()<< "]"<<endl; 115 return output; 116 } 117 118 void main() 119 { 120 Point p ( 72, 115 ) ; //定义点对象并初始化 121 cout << "The initial location of p is " << p << endl ; 122 p.setPoint ( 10, 10 ) ; //置点的新数据值 123 cout << " The new location of p is " << p << endl ; //输出数据 124 Circle c ( 2.5, 37, 43 ) ; //定义圆对象并初始化 125 cout<<" The initial location and radius of c are "<<c<<" Area = "<<c.getArea()<<" " ; 126 //置圆的新数据值 127 c.setRadius ( 4.25 ) ; 128 c.setPoint ( 2, 2 ) ; 129 //输出圆心坐标和圆面积 130 cout<<" The new location and radius of c are "<<c<<" Area = "<<c.getArea()<< " " ; 131 Cylinder cyl ( 5.7, 2.5, 12, 23 ) ; //定义圆柱体对象并初始化 132 //输出圆柱体各数据和表面积，体积 133 cout << " The initial location, radius ang height of cyl are " << cyl 134 << "Area = " << cyl.getArea() << " Volume = " << cyl.getVolume() << ' '; 135 //置圆柱体的新数据值 136 cyl.setHeight ( 10 ) ; 137 cyl.setRadius ( 4.25 ) ; 138 cyl.setPoint ( 2, 2 ) ; 139 cout << " The new location, radius ang height of cyl are " << cyl 140 << "Area = " << cyl.getArea() << " Volume = "<<cyl.getVolume()<< " " ; 141 }