When to use fflush()?

[Roger A. Cornelius]

When should you use fflush()? OR are there any guarantees of
when output buffers are flushed?  I have a program that uses
fputs() to print a prompt, then waits for a return to be typed.
The prompt is always displayed, but am I guaranteed of this?
Should I use fflush() anyway?  What's the rule for when to use
fflush(), and when it's not needed?

Thanks, Roger
--
Roger A. Cornelius           rac at sherpa            uunet!sherpa!rac