Sleep () delays my program too early. What am I doing wrong?

Question

I want to write a small program that should print something like

CPU testing ... done
RAM testing ... done

etc.

I wrote the following program in C:

printf( "testing RAM...\t\t" ); sleep( sleep_time ); printf( "done\n\n" ); printf( "testing HDD...\t\t" ); sleep( sleep_time ); printf( "done\n\n" ); 

where sleep_time is 2.

However, instead of first typing “CPU testing ...”, then waiting, and then typing “done,” it first waits and then prints the entire line, which is not quite what I had in mind.

I believe this is due to automatic compiler optimization.
Anyway, what can I do to get the desired result?

I am using Xcode 3.1 in OSX 10.5.6

Thanks,
Bastian

Answer 1

The problem is that your prints are buffered. just before bedtime, call fflush (stdout); to flush the buffer

Answer 2

the compiler cannot reorder and sleep, as they are the "externally observable behavior" of the abstract C machine.

What you get is related to stdout buffering. You can use fflush or print for stderr, which is not buffered.

Answer 3

Just using \ n or endl at the end of the first printf should be enough