重载运算符<<。 这个操作员不是班级的朋友

Question

I have to overload:

ostream& operator<<();

This must be implement as method so I can't do it as friend. How to do it?

Answer 1

If you will write this operator as a member function then it will only confuse users because the left operand of the operator will be an object of your class type instead of std::ostream. So you could write your own member function instead of the operator. For example

class YourClass
{
public:
   std::ostream & out( std::ostream &os ) const
   {
      // some output
      return os;
   }
//...
};

You could also use this function inside the definition of the operator as a non-member function of the class. For example

std::ostream & operator <<( std::ostream &os, const YourClass &obj )
{
   return obj.out( os );
}