C++ 设计一个圆类,计算圆的面积和周长.

1.
class Circle
{
public:
Circle():r(0), leng(0), area(0){
}
Circle(const int rm):r(rm){
leng = 2 * pi * rm;
area = pi * rm * rm;
}
Circle& Circle(Circle& other){
r = other.r;
leng = other.leng;
area = other.area;
return *this;
}
void setR(const double rm)
{
r = rm;
leng = 2 * pi * r;
area = pi * r * r;
}
void output()
{
cout