#include<iostream>
using namespace std;
const double PI=3.14;
class circle
{
public:
circle(double x);
circle ();
void setdata(double x);
void showdata();
double get();
circle (circle &p);
~circle (){}
private :
double area,s;
};最后两个打不出来结果是为什么
circle ::circle(double x)
{
area=x;
}
circle::circle ()
{
area=0;
}
void circle ::setdata(double x)
{
area=x;
s=PI*area*area ;
}
void circle::showdata()
{
cout <<s<<endl;
}
double circle::get()
{
return area;
}
circle ::circle (circle& p)
{
area=p.area;
}
void main()
{
circle a;
a.setdata(3);
a.showdata();
circle p(3);
p .showdata();
circle b=p;
circle ();
b.showdata();
}

来咯了了了了了了了了了了了了了了了了了了了啦啦啦