#include
using namespace std;
class circle{
private:
double radius;
public:
circle(double r=0.0);
void input();
double c();
double s();
};
circle ::circle (double r)
{ radius =r;
}
void circle::input()
{ cout<<"请输入半径:"<
}
double circle::c()
{ return 2*3.14*radius;
}
double circle::s()
{ return 3.14*radius*radius;
}
int main()
{ circle A;
A.input();
cout<<"圆的周长为"<
return 0;
}