c - Is manually requesting buffering necessary? -

is necessary call functions setbuf() , setvbuf() when open file streams adjust buffering?
isn't i/o buffering handled automatically?

no, buffering handled automatically, maybe not in fashion want or need.

you might want flushing on each write, on newline, on full buffer, , default wrong case.

or might want bigger buffer efficiency.

in cases, adjust default.
though, in general default sensible, , can left alone.

here case automatic sniffer failed badly:
printf statement not executing before scanf statement in netbean