Date: Thu, 13 Jan 2000 10:22:34 -0500 From: Naief BinTalal <naief@cyfari.com> To: "Alexey N. Dokuchaev" <danfe@ssc.nsu.ru> Cc: freebsd-questions@FreeBSD.org Subject: Re: (void)printf(); (Was: Re: simple c i/o question) Message-ID: <20000113102234.A45156@cyfari.com> In-Reply-To: <Pine.LNX.4.10.10001131324520.22433-100000@inet.ssc.nsu.ru>; from danfe@ssc.nsu.ru on Thu, Jan 13, 2000 at 01:28:08PM %2B0600 References: <20000112114019.A93129@cyfari.com> <Pine.LNX.4.10.10001131324520.22433-100000@inet.ssc.nsu.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Jan 13, 2000 at 01:28:08PM +0600, Alexey N. Dokuchaev wrote:
> On Wed, 12 Jan 2000, Naief BinTalal wrote:
>
> > On Wed, Jan 12, 2000 at 04:28:23PM +0000, Jonathon McKitrick wrote:
> > >
> > > I'm trying to write a hello world program. What is the output file for
> > > the console currently being displayed (in other words, the screen)?
> > > I've tried printf, and fprintf to stdout and stderr.
> >
> > #include <stdio.h>
> >
> > int
> > main(void)
> > {
> > (void)fprintf(stdout,"Hello World\n");
> > return 0;
> > }
> >
>
> While browsing thru the source code of almost anything in FreeBSD, I've
> noticed that (type)function(parameters); syntax. Why not just to write
> function(paramenters). Like in the prev example, what's wrong with simple
> printf(blahblah); but (void)printf(blahblah); ?
>
Hi Alexey
When you write (void)function(Whatever); you are casting the return
value to void. This _explicitly_ says that you the programmer know
that the function returns a value but choose to ignore it.
That's all. It's a better way of programming.
By the way I can tell that you have reached that level where obscure
language features that you don't know bother you ;>. Well the only way
is to read the standard or you take a look at books which go through the
standard bit by bit.
A good book on this is "C, A Reference Manual" by Samuel P. Harbison
and Guy L. Steele Jr.
Hope this helps
Cheers
Naief
BBTG
> Thanx.
>
>
> ,--------------------------------------, ____ ___ _______
> | Alexey N. Dokuchaev, more commonly | / __/______ ___ / _ )/ __/ _ \
> | known as DAN Fe | / _// __/ -_) -_) _ |\ \/ // /
> | | /_/ /_/ \__/\__/____/___/____/
> | Novosibirsk State University `-------- The Power to Serve --------,
> | Scientific Study Center Computer Lab |
> | |
> | email: danfe@inet.ssc.nsu.ru homepage: http://inet.ssc.nsu.ru/~danfe/ |
> | ICQ UIN: 38934845 |
> `---------------------------------------------------------------------------'
>
> A good conspiracy is unprovable. I mean, if you can prove it, it means they
> screwed up somewhere along the line.
>
> Jerry Fletcher from Conspiracy Theory
>
--
-------------------------------------------------------
Naief BinTalal | naief@cyfari.com
-------------------------------------------------------
"A rock pile ceases to be a rock pile the moment a
single man contemplates it, bearing within him the
image of a cathedral" -- Antoine de Saint-Exupery
-------------------------------------------------------
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20000113102234.A45156>