Why we can't use endl when we use std::cout enstand of cout ?

Answer 1

Actually Dlite , one can only omit the "std::" with the statement:

using namespace std;

and also using the include statement with or without the using statement.

Answer 2

std::endl, std::cout

In case you include the preprocessing directive

#include <iostream>,
then you can simply use. cout, endl without prepending "std::"