ostream& operator<<(ostream& os, const ClassType *object)
{//...os << //...return os;
}

istream& operator>>(istream& in, Sales_Item& s)
{double price;in >> s.isbn >> s.units_sold >> price;if (in)s.revenue = s.units_sold * price;elses = Sales_item(); //input failed:reset object to default statereturn in;
}

Sales_item operator+(const Salse_item& lhs, const Salse_item& rhs)
{Sales_item ret(lhs);ret += rhs;  //非常好用的方法return ret;
}

inline bool
operator==(const ClassType &lhs, const ClassType &rhs)
{return ...
}
inline bool
operator!=(const ClassType &lhs, const ClassType &rhs)
{return !(lhs == rhs);
}

class Foo
{
public:int &operator[](const size_t);const int &operator[](const size_t) const;//...
private:vector<int> data;
};int& Foo::operator[](const size_t index)
{return data[index]; //注意，这里没有进行下标越界检查
}
const int& Foo::operator [](const size_t index) const
{return data[index];
}

#include "iostream"
#include "stdio.h"
using namespace std;
class ScreenPtr;
class Screen //用于ScreenPtr中操作对象的类
{
public:Screen(){cout << "In Screen" << endl;}void display(){cout << "In Screen Display" << endl;}
};
class ScrPtr //智能指针，用来管理ScreenPtr类中要操作对象的类的指针
{friend class ScreenPtr;Screen *sp;size_t use;ScrPtr(Screen *p):sp(p), use(1) {}~ScrPtr() {delete sp;}
};class ScreenPtr
{
public:ScreenPtr(Screen *p):ptr(new ScrPtr(p)) {}ScreenPtr(const ScreenPtr &orig):ptr(orig.ptr) //复制构造函数{++ptr->use;}ScreenPtr& operator=(const ScreenPtr&){}~ScreenPtr(){if (--ptr->use == 0){delete ptr;}cout << "In ScreenPtr" << endl;}
public:Screen& operator*(){return *ptr->sp;}Screen* operator->(){return ptr->sp;}const Screen& operator*() const{return *ptr->sp;}const Screen* operator->() const{return ptr->sp;}
private:ScrPtr *ptr;
};int main()
{Screen *myscreen = new Screen();ScreenPtr p(myscreen);p->display();return 0;
}