The consequences and pros/cons of flushing the stream in c++

Question

I have recently read an article which stated that using \\n is preferable to using std::endl because endl also flushes the stream.

Answer 1

It is preferable to flush the buffer if you need the target of your stream to receive the data before the stream is closed.

A real-life example would be an application log, written from a stream that's always open... You may want to look at this log while the program is still running.