c++ How to not use friend declaration when equipping a class with `operator<<`

Here's a way to equip a class with the operator<< without using the friend declaration:

1. Create a class with private members and a public function to access those members:

class MyClass {
private:
    int data;

public:
    MyClass(int d) : data(d) {}
    int getData() const { return data; }
};

1. Define the operator<< function outside the class as a non-member function:

#include <iostream>

void operator<<(std::ostream& os, const MyClass& obj) {
    os << obj.getData();
}

This implementation allows operator<< to access the class's private members through the public member function getData().