program menghitung volume bola

#include <iostream.h>
#include <conio.h>
class Volume {
friend ostream& operator<<(ostream&, const Volume&);
friend istream& operator>>(istream&, Volume&);
public:
Volume();
void volume_bola(){vol=(4/3)*(3.14*r*r*r);}
private:
int r;
int vol;
};
Volume::Volume(){
cout<<”Program menghitung volume bola\n”;
cout<<”Selamat mencoba\n”;
}
istream& operator>>(istream& in, Volume& masukkan){
cout<<”Masukkan nilai r :”;
in>>masukkan.r;
return in;
}
ostream& operator<<(ostream& out, const Volume& keluaran){
out<<”Nilai r :”<<keluaran.r<<endl;
out<<”volume bola :”<<keluaran.vol<<endl;
return out;
}
main(){
Volume X;
cin>>X;
X.volume_bola();
cout<<X;
getch();
return 0;
}