Demo: printf vs write

printf() sits at the top of the C library's output stack: it parses a format string, manages a FILE object, keeps a buffer, and only at the very bottom calls write(). write() is the other end of that stack: no formatting, no buffering, every call hands the bytes straight to the operating system. So printf() does strictly more work than write() - and yet the answer to "which one is faster?" is it depends on one line of code.

Together with the teaching assistant you will fill in the TODOs in printf_demo.c and write_demo.c, time both programs, comment out a single line, and use strace to see what actually reaches the operating system.