#include <cstdlib> #include <iostream> using namespace std; class volum{ friend ostream& operator<<(ostream&, const volum&); friend istream& operator>>(istream&, volum&); public: volum(); void volum_bola(){vb =(4/3*3.14*r*r*r);} private: double r, vb; }; volum::volum(){ cout<<"menghitung volum bola"<<endl; } istream& operator >>(istream& in, volum& masuk){ cout<<"masukkan jari jari : "; in>> masuk.r; return in; } ostream& operator<<(ostream& out, const volum& keluar){ ...