Path: utzoo!utgpu!watmath!att!dptg!rutgers!iuvax!purdue!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: When to use fflush()?
Keywords: fflush
Message-ID: <10882@smoke.BRL.MIL>
Date: 30 Aug 89 21:46:23 GMT
References: <143@sherpa.uucp>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 20

In article <143@sherpa.uucp> rac@sherpa.uucp (Roger A. Cornelius) writes:
>When should you use fflush()? OR are there any guarantees of
>when output buffers are flushed?

Use fflush() whenever you want to make sure that the buffers are forced out.

>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?

Recent versions of stdio attempt to force out all output possibly associated
with a "terminal" whenever input is requested from a "terminal".  It is not
always possible to tell what is really a terminal, though.  Modern stdio
also defaults to line-buffered output on "terminals", although that wouldn't
help for a prompt on the same line as the input.

>Should I use fflush() anyway?  What's the rule for when to use
>fflush(), and when it's not needed?

See my first sentence.