using?namespace?std;
#define?PI?3.141592635
class?Circle
{
public:
Circle()?:?_r(0.f){}
Circle(double?r)?:?_r(r){}
Circle(const?Circle&?circle)
{
this->_r?=?circle._r;
}
void?setRadius(double?r)
{
this->_r?=?r;?
}?
double?Area()
{
return?PI?*?this->_r?*?this->_r;?
}
double?Circumference()
{
return?2?*?PI?*?this->_r;?
}?
private:
double?_r;?
};?
int?main()
{
Circle?c1;
double?x;
cin?>>?x;
c1.setRadius(x);
cout?<<?"c1面積："?<<?c1.Area()?<<?endl;
cout?<<?"c1周長："?<<?c1.Circumference()?<<?endl;
Circle?c2(2?*?x);?
cout?<<?"c2面積："?<<?c2.Area()?<<?endl;
cout?<<?"c2周長："?<<?c2.Circumference()?<<?endl;?
Circle?c3(c1);?
cout?<<?"c3面積："?<<?c3.Area()?<<?endl;
cout?<<?"c3周長："?<<?c3.Circumference()?<<?endl;?
return?0;?
}