From owner-freebsd-questions@FreeBSD.ORG  Wed Aug 11 09:42:55 2004
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 0454916A4CE
	for <freebsd-questions@freebsd.org>;
	Wed, 11 Aug 2004 09:42:55 +0000 (GMT)
Received: from kane.otenet.gr (kane.otenet.gr [195.170.0.27])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 0842743D48
	for <freebsd-questions@freebsd.org>;
	Wed, 11 Aug 2004 09:42:53 +0000 (GMT)
	(envelope-from keramida@ceid.upatras.gr)
Received: from orion.daedalusnetworks.priv (aris.bedc.ondsl.gr
	[62.103.39.226])i7B9gn1D032402;	Wed, 11 Aug 2004 12:42:50 +0300
Received: from orion.daedalusnetworks.priv (orion [127.0.0.1])
	i7B9gj45031362;	Wed, 11 Aug 2004 12:42:46 +0300 (EEST)
	(envelope-from keramida@ceid.upatras.gr)
Received: (from keramida@localhost)i7B9girb031361;
	Wed, 11 Aug 2004 12:42:44 +0300 (EEST)
	(envelope-from keramida@ceid.upatras.gr)
Date: Wed, 11 Aug 2004 12:42:44 +0300
From: Giorgos Keramidas <keramida@ceid.upatras.gr>
To: Mipam <mipam@ibb.net>
Message-ID: <20040811094244.GA30843@orion.daedalusnetworks.priv>
References: <20040810171119.GA26303@orion.daedalusnetworks.priv>
	<Pine.BSO.4.56.0408111039230.11899@ux11.ltcm.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Pine.BSO.4.56.0408111039230.11899@ux11.ltcm.net>
cc: freebsd-questions@freebsd.org
Subject: Re: localtime question
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>,
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>,
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 11 Aug 2004 09:42:55 -0000

On 2004-08-11 10:44, Mipam <mipam@ibb.net> wrote:
> > You'd have to use strftime() and a local buffer for that.
>
> I found an example and adjusted it:
>
> #include <time.h>
> #include <stdio.h>
>
> int main()
> {
>     struct tm *ptr;
>     time_t tm;
>     char str[60];
>     char str2[60];
>     char str3[60];
>
>     tm = time(NULL)-86400;
>     ptr = localtime(&tm);
>     strftime(str ,100 , "%d",ptr);
>     strftime(str2 ,100 , "%m",ptr);
>     strftime(str3 ,100 , "%Y",ptr);
>     printf("%s %s %s\n",str3,str2,str);
>
>     return 0;
> }
>
> This runs just fine: 2004 08 10
> I dont know what the 100 is good for?

It's the size of the buffer that strftime() gets as the first argument.
In this case 100 is a bug waiting to happen, because the buffers are
allocated with only 60 bytes of data.  The manpage of strftime()
explains what each argument is supposed to be.

        $ man strftime

> I compiled both with: cc -O3 -mcpu=pentiumpro -o time time.c
> Both compile without errors.

Note that -O3 might be a it unsafe on FreeBSD.
Even -O2 is not always a good idea.