Operator overloading 如何超载<&书信电报；基于已定义的方法显示的运算符？

我想重载您定义的操作符

#include <iostream>

using namespace std;

class MyClass
{
public:

  MyClass()
  {}

  ostream& display(ostream& out) const
  {
    out << "Display message" << endl;
    return out;
  }

  ostream& operator<< (ostream& out) const
  {
    ostream& output = display(out);
    return output;
  } 
};

int main()
{
  MyClass C1;
  cout << C1 << endl; 

  return 0;
}

C1 << cout;

cout << C1;

ostream& operator<< (ostream& out, const MyClass& c) { ... }

cout << C1;