overloading post test 2 slot 15.00

#include<iostream>
using namespace std;

class luas{
friend ostream& operator << (ostream&, luas&);
friend istream& operator >> (istream&, luas&);

public:
luas(){
r = 0;
phi = 3.14;
t = 0;
l = 0;
}
float tabung(){

l = 2 * phi * r * (r + t);
return l;
}
private:
int r,t;
float phi, l;
};

ostream& operator << (ostream& posttest2, luas& lingk){
posttest2 << "r = :"<<lingk.r<<endl;
posttest2 << "t = :"<<lingk.t<<endl;
posttest2<< "luas adalah\t"<<lingk.tabung();
}

istream& operator >> (istream& masuk, luas& aran){
cout<<"masukkan r =";
masuk >> aran.r;
cout<<"masukkan t =";
masuk >> aran.t;
return masuk;
}
main(){
luas x; //nama class beserta
cin>>x;
cout<<x;
}