如何将基类的重载运算符函数调用为派生类的重载运算符函数

【问题标题】：how do i call the overloaded operator function of a base class into that of a derived class如何将基类的重载运算符函数调用为派生类的重载运算符函数
【发布时间】：2014-12-14 08:02:42
【问题描述】：

class Vehicle{
long Number;
int Year;
char *Make,*Model,*BodyStyle,*Color;
float Cost;
friend ostream & operator<<(ostream& stream,const Vehicle& v);

class TruckVehicle:public Vehicle{
int Passengers;
long Mileage,GrossWeight,TempGross;
char *PoweredBy;

friend ostream & operator<<(ostream& stream,const TruckVehicle& t )

在上面的代码中..如何将基类的重载

【问题讨论】：

标签： c++ class oop object operator-overloading

【解决方案1】：

最简单和最干净的方法是：-

class Base
{
  public:
      virtual ostream& put(ostream& s) const = 0;
};

ostream& operator<<(ostream& s, const Base& r)
{
    return r.put(s);
}

class Derived : public Base
{
  public:
      ostream& put(ostream& s) const;
};

void f(const Base b, Derived d)
{
    cout << b << d;
}

即 put() 是一个虚函数，可确保在中使用正确的输出操作

【讨论】：

friend ostream & operator(t);流
virtual ostream& put(ostream& s) const = 0; 然后const Base b?