双色球红球麒麟图解:C++ 帮我看看这程序哪错了

#include<iostream.h>

class Column
{
friend void print(Column &);
friend void setData(Column &,double,double,double,double);
public:
Column(double x,double y,double r,double h);
~Column();
double area();
double volumn();//体积

private:
double height;
double radius;
double x;
double y;
};

Column::Column(double x,double y,double r,double h)
{
// x=y=r=h=0;
height=h;
radius=r;
}

double Column::area()
{
double area;
double const PI=3.1415926;
area=2*PI*C.radius*C.height+2*PI*C.radius*C.radius;
return area;
}

double Column::volumn()
{
double const PI=3.1415926;
return(C.radius*C.radius*PI*C.height);
}

void setData(Column &C,double x,double y,double r,double h)
{

C.x=x;
C.y=y;
C.height=h;
C.radius=r;
}

void print(Column C)
{
char key;
double x,y,r,h;
cout<<"x: ";
cin>>x;
cout<<endl<<"y: ";
cin>>y;
cout<<endl<<"h: ";
cin>>h;
cout<<endl<<"r: ";
cin>>r;
setData(C,x,y,r,h);
cout<<endl<<endl
<<"1.area"<<endl
<<"2.vlumn"<<endl;
cin >>key;
if(key=='1')
{
double area;
area=C.area();
cout<<area<<endl;
}
else
if(key=='2')
{
double v;
v=C.volumn();
cout<<v<<endl;
}
else
cout<<"输入错误"<<endl;
print(C);
}

void main()
{
Column C(0,0,0,0);
print(C);
}