Cout in C ++

In other words, we should all understand that this is implemented by reloading the operator <function.

Cout <123; cout <"ssss ";

But like

Cout <Endl;

How is it implemented?

At first, I guess Endl is a class or struct, and then implemented through a friend function.

But let's look at the implementation of STL. Originally, Endl is a function!

Template <typename _ chart, typename _ traits> inline basic_ostream <_ chart, _ traits> & Endl (basic_ostream <_ chart, _ traits> & _ OS) {return flush (_ OS. put (_ OS. widen ('\ n') ;}__ ostream_type & operator <(_ ostream_type & (* _ pF) (_ ostream_type &)) {return _ pF (* This );}

When cout <Endl is used, the flush function is called once.

From the followingCodeWe can also see one or two implementation principles.

Cout. Operator <(Endl );