.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 19:49:27 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Fri Apr 26 12:38:55 MET DST 1996 by Martin Schulze (joey@linux.de)
.\" Modified 2001-11-13, aeb
.\" Modified 2004-11-16, mtk
.\"
.\" Japanese Version Copyright (c) 1997 Hiroaki Nagoya
.\"         all rights reserved.
.\" Translated 1997-02-10, Hiroaki Nagoya <nagoya@is.titech.ac.jp>
.\" Updated 1999-09-01, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2001-10-15, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2001-12-13, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2002-01-03, Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-02-24, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2008-04-04, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.79
.\" Updated 2008-08-08, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v3.05
.\" Updated 2008-11-10, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v3.13
.\"
.\"WORD: Coordinated Univarsal Time  
.\"WORD: broken-down time  ̤λ
.\"
.TH CTIME 3 2009-03-15 "" "Linux Programmer's Manual"
.SH ̾
asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r,
localtime_r \- դȻ̤λ ASCII Ѵ
.SH 
.nf
.B #include <time.h>
.sp
.BI "char *asctime(const struct tm *" tm );
.br
.BI "char *asctime_r(const struct tm *" tm ", char *" buf );
.sp
.BI "char *ctime(const time_t *" timep );
.br
.BI "char *ctime_r(const time_t *" timep ", char *" buf );
.sp
.BI "struct tm *gmtime(const time_t *" timep );
.br
.BI "struct tm *gmtime_r(const time_t *" timep ", struct tm *" result );
.sp
.BI "struct tm *localtime(const time_t *" timep );
.br
.BI "struct tm *localtime_r(const time_t *" timep ", struct tm *" result );
.sp
.BI "time_t mktime(struct tm *" tm );
.fi
.sp
.in -4n
glibc εǽޥ׷
.RB ( feature_test_macros (7)
):
.in
.sp
.BR asctime_r (),
.BR ctime_r (),
.BR gmtime_r (),
.BR localtime_r ():
.br
_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _BSD_SOURCE ||
_SVID_SOURCE || _POSIX_SOURCE
.SH 
ؿ
.BR ctime (),
.BR gmtime (),
.BR localtime ()

\fItime_t\fP ΥˤȤ롣
ϡ (UTC) 1970 ǯ 1  1  00:00:00
ηвÿȲᤵ롣
.PP
ؿ
.BR asctime ()

.BR mktime ()

ǯʤɤʬΥ줿̤λȤ롣
.PP
̤λ \fI<time.h>\fP ǰʲΤ褦Ƥ
\fItm\fP ¤Τݻ롣
.sp
.in +4n
.nf
struct tm {
    int tm_sec;         /*  */
    int tm_min;         /* ʬ */
    int tm_hour;        /*  */
    int tm_mday;        /*  */
    int tm_mon;         /*  */
    int tm_year;        /* ǯ */
    int tm_wday;        /*  */
    int tm_yday;        /* ǯ̻ */
    int tm_isdst;       /* ƻ */
};
.fi
.in
.PP
\fItm\fP ¤ΤΥСϰʲ̤:
.TP 10
.I tm_sec
ÿդĤ 0  59 ޤǤ͡
äΤ 60 ޤǤͤϵ롣
.TP
.I tm_min
ʬ0  59 ޤǤ͡
.TP
.I tm_hour
椫̻֡0  23 ޤǤ͡
.TP
.I tm_mday
Ϥᤫ1  31 ޤǤ͡
.TP
.I tm_mon
1̻0  11 ޤǤ͡
.TP
.I tm_year
1900 ǯ̻ǯ
.TP
.I tm_wday
̻()0  6 ޤǤ͡
.TP
.I tm_yday
1  1 ̻0  365 ޤǤ͡
.TP
.I tm_isdst
ƻ֤ͭɤΥե饰
ͤʤвƻ֤ͭˤʤꡢ0 ʤ̵ͤʤФξˤ
̣ʤ
.PP
.BI ctime( t )
ؿϡ
.BI asctime(localtime( t ))
Ǥ롣
 \fIt\fP 
.sp
.RS
"Wed Jun 30 21:49:08 1993\\n"
.RE
.sp
Ȥ NULL ü줿ʸѴ롣
άΤ
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" Ǥ롣
άΤ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
"Sep", "Oct", "Nov", "Dec" Ǥ롣
֤ͤϡŪ (static) ˳Ƥ줿ʸؤΥݥ󥿤Ǥ롣
ʸϡաؿΤ줫ƤӽФȾ񤭤뤳Ȥ롣
ޤδؿѿ \fItzname\fP, \fItimezone\fP, \fIdaylight\fP
˸ߤΥॾξꤹ
.RB ( tzset (3)
)
ꥨȥǤǤ
.BR ctime_r ()
Ʊͤ
ʸϥ桼ѰդХåե˳Ǽ롣ХåեΥ
ʤȤ 26 ХȰʾǤʤФʤʤ
δؿ \fItzname\fP, \fItimezone\fP, and \fIdaylight\fP
ꤹɬפϤʤ
.PP
ؿ
.BR gmtime ()
ϡ \fItimep\fP 
 (UTC) Ǥ̤λѴ롣
ǯ˼ޤʤ硢NULL ֤
֤ͤŪ˳ݤ줿¤ΤؤƤꡢθ
դ˴ؤؿΤ줫ƤӽФ
񤭤ǽ롣
.BR gmtime_r ()
Ʊͤ
ǡϥ桼Ѱդ¤Τ˳Ǽ롣
.PP
ؿ
.BR localtime ()
ϡ桼ꤷॾǤλǤѴ롣
δؿ
.BR tzset (3)
ƤӽФΤ褦˿񤤡
ѿ \fItzname\fP ˸ߤΥॾξꤹ롣
ޤ\fItimezone\fP ˶ (UTC) ȥɸȤ
ÿꤷ
ǯΰDzƻ֤ŬѤ \fIdaylight\fP  0 ꤵ롣
֤ͤŪ˳ݤ줿¤ΤؤƤꡢθ
դ˴ؤؿΤ줫ƤӽФ
񤭤ǽ롣
.BR localtime_r ()
Ʊͤ
ǡϥ桼Ѱդ¤Τ˳Ǽ롣
δؿ \fItzname\fP, \fItimezone\fP, and \fIdaylight\fP
ꤹɬפϤʤ
.PP
ؿ
.BR asctime ()
ϡ̤λ \fItm\fP 
.BR ctime ()
Ʊ NULL ü줿ʸѴ롣
֤ͤŪ˳Ƥ줿ʸؤΥݥ󥿤Ǥ롣ʸϡ
աؿΤ줫ƤӽФȾ񤭤뤳Ȥ롣
ꥨȥǤǤ
.BR asctime_r ()
Ʊͤ
ʸϥ桼ѰդХåե˳Ǽ롣ХåեΥ
ʤȤ 26 ХȰʾǤʤФʤʤ
.PP
ؿ
.BR mktime ()
ϡ(륿ǵҤƤ) ̤λ
Ѵ롣κݡƤӽФե
.I tm_wday

.I tm_yday
ǻꤷ̵ͤ뤵롣
.BR mktime ()
ϡե
.I tm_isdst
ǻꤵ줿ͤˤꡢ
.I tm
¤ΤϤ줿Dzƻ (daylight saving time; DST) ͭˤʤä
뤫Τ롣
ͤϲƻ֤ͭǤ뤳Ȥ̣롣
ͤǤС
.BR mktime ()
 (ॾȥƥΥǡ١Ȥä)
ꤵ줿Dzƻ֤ͭɤȽǤɬפ뤳Ȥ̣롣

.BR mktime ()

.I tm
¤ΤγƥեɤʲΤ褦˽롣
.I tm_wday

.I tm_yday
ˤ¾ΥեɤƤ᤿ͤꤹ롣
¤ΤǤͭϰϤˤʤ硢
(㤨С10  40  11  9 ѹ)
.I tm_isdst
ˤ (ǽͤˤ餺) ͤ 0 ꤵ롣
ͤϻꤵ줿֤Dzƻ֤ͭǤ뤳Ȥ򼨤
0 ̵Ǥ뤳Ȥ򼨤
ؿ
.BR mktime ()
ƤӽФȡ
ѿ \fItzname\fP ߤΥॾꤵ롣

̤λ򥫥 ( (Epoch) ÿ) ɽǤʤ硢
.BR mktime ()

.I (time_t)\ (-1)
֤̤λι¤ΥСѹʤ
.SH ֤
ƴؿϤ줾Ҥ֤ͤ顼ξ NULL
.RB ( mktime ()
Ǥ \-1) ֤
.SH 
POSIX.1-2001.
C89  C99 Ǥ
.BR asctime (),
.BR ctime (),
.BR gmtime (),
.BR localtime (),
.BR mktime ()
ꤵƤ롣
POSIX.1-2008 ϡ
.BR asctime (),
.BR asctime_r (),
.BR ctime (),
.BR ctime_r ()
ѻͽȤƤ롣
ˡ
.BR strftime (3)
λѤ侩Ƥ롣
.SH 
.BR asctime (),
.BR ctime (),
.BR gmtime (),
.BR localtime ()
 4 ĤδؿŪǡؤΥݥ󥿤֤ΤǡåɥդǤϤʤ
δؿΥåɥǤǤ
.BR asctime_r (),
.BR ctime_r (),
.BR gmtime_r (),
.BR localtime_r ()
 SUSv2 ǵꤵƤꡢ
libc 5.2.5 ʹߤѤǤ롣

POSIX.1-2001 Ǥϡִؿ
.BR asctime (),
.BR ctime (),
.BR gmtime (),
.BR localtime ()
ϡ̤λι¤Τ
.I char
󤫤Τɤ餫Ū֥Ȥ֤ΤȤ롣
δؿΤ줫¹Ԥȡ¾δؿΤɤ줫
Ū֥ȤΤɤ餫˳Ǽ֤󤬾񤭤뤫
ʤפȤʤäƤ롣
ΤȤ glibc μǵꤦ롣
.LP
glibc ޤ¿μǤϡ
.I tm_mday
 0 ꤹκǽ̣ƤȲᤵ롣
.LP
glibc Ǥϡ
.I <time.h>
󥯥롼ɤ
.B _BSD_SOURCE
ȡ
\fIstruct tm\fP ˰ʲΥեɤɲä롣
.sp
.RS
.nf
long tm_gmtoff;           /* Seconds east of UTC */
const char *tm_zone;      /* Timezone abbreviation */
.fi
.RE
.sp
 BSD ĥǤꡢ4.3BSD-Reno 鸽줿

POSIX.1-2004 ˤȡ
.BR localtime ()
Ϥ
.BR tzset ()
ƤФ줿Τ褦˿񤦤Ȥ׵ᤵƤ뤬
.BR localtime_r ()
ˤϤ׷Ϥʤ
.\" http://thread.gmane.org/gmane.comp.time.tz/2034/ 򻲾ȡ
ܿɬפʥɤǤϡ
.BR localtime_r ()

.BR tzset ()
ƤӽФƤ٤Ǥ롣
.SH Ϣ
.BR date (1),
.BR gettimeofday (2),
.BR time (2),
.BR utime (2),
.BR clock (3),
.BR difftime (3),
.BR strftime (3),
.BR strptime (3),
.BR timegm (3),
.BR tzset (3),
.BR time (7)