Difference between << / >> operator overloading and Input/Output functions

Question

I would really appreciate if someone could explain to me the difference between overloading the input/output operators, for example:

friend ostream& operator<<(ostream& ost, const myClass& obj) {
    return ost << obj.x << obj.y;
}

and Output/Input functions like these:

void Output(ostream& ost) {
    ost << x << y;
}

What are they used for, examples etc. Everything is acceptable. Thanks!

Answer 1

Overloading the << operator will allow you to chain output operations:

myClass a, b;

...

cout << a << ' ' << b;

Using your alternate implementation, you would have to write:

myClass a, b;

...

a.Output(cout);
cout << ' ';
a.Output(b);

The first version makes it easier to quickly see how the output will be formatted. It is also the standard way to use streams in C++.