3.22和3.23

3.22

#include<iostream>using namespace std;const double PI=3.14;class Circle{public:Circle(int r){radius=r;}double area(){return(PI*radius*radius);}private:int radius;};int main(){Circle r1(10);r1.area();cout<<"the Circle's area is"<<r1.area()<<endl;return 0;}

3.23

#include<iostream>using namespace std;const double PI=3.14;class cylinder{public:cylinder(double r,double h){radius=r;high=h;}double v(){return(PI*radius*radius*high);}void vol(){cout<<"the cylinder's v is"<<'\t'<<v()<<endl;}private:double radius;double high;};int main(){cylinder v1(4.2,5.5);v1.v();v1.vol();cylinder v2(3,6);v2.v();v2.vol();return 0;}