源程序：
//1.設計一個基類，從基類派生圓柱，設計成員函數輸出它們的面積和體積；
#include < iostream >
using namespace std;
class Basic//基類
{
protected:
double r;
public:
Basic() { r = 0; }
Basic(double a) :r(a) {}
};
class Circular : public Basic//從基類派生圓類
{
protected:
double area;
public:
Circular(double a)
{
r = a;
area = area = 3.1415926 * r * r;
}
double getArea()//返回圓面積
{
return area;
}
};
class Column : public Circular//從圓類派生圓柱類
{
protected:
double h;
double cubage;
public:
Column(double a, double b) : Circular(a)
{
h = b;
cubage = getArea() * h;
}
double getCubage()//返回圓柱體積函數
{
return cubage;
}
};
void main()
{
Circular circular(45);
Column column(12, 10);
cout << "圓的面積：" << circular.getArea() << endl;
cout << "圓柱的體積：" << column.getCubage() << endl;
system("pause");
}
運行結果：
