Which is the best way to print to the console in c++?

Question

I have read three ways to print things to the console in c++ from various sources.

1. Using using namespace std; and then using cout (CodeBlocks Standard)
2. Not using the above and using std::cout and std::endl; (C++ Primer)
3. Using printf (HackerRank)

Which is preferred and why?

Answer 1

Number 2 with amendment. (std::cout and '\n')

Why?

1. Because you should avoid using namespace std. Source
2. (Among other reasons) Because cout is typesafe and printf is not. Source
3. std::endl will force a flush of the output buffer to the console. Unless you specifically want this to happen use << '\n' or << "...string\n". Source