2.9BSD/usr/man/cat3/ctime.3

CTIME(3)            UNIX Programmer's Manual             CTIME(3)

NAME
     ctime, localtime, gmtime, asctime, timezone -  convert date
     and time to ASCII

SYNOPSIS
     char *ctime(clock)
     long *clock;

     #include <time.h>

     struct tm *localtime(clock)
     long *clock;

     struct tm *gmtime(clock)
     long *clock;

     char *asctime(tm)
     struct tm *tm;

     char *timezone(zone, dst)

DESCRIPTION
     _C_t_i_m_e converts a time pointed to by _c_l_o_c_k such as returned
     by _t_i_m_e(2) into ASCII and returns a pointer to a 26-
     character string in the following form.  All the fields have
     constant width.

         Sun Sep 16 01:03:52 1973\n\0

     _L_o_c_a_l_t_i_m_e and _g_m_t_i_m_e return pointers to structures contain-
     ing the broken-down time.  _L_o_c_a_l_t_i_m_e corrects for the time
     zone and possible daylight savings time; _g_m_t_i_m_e converts
     directly to GMT, which is the time UNIX uses.  _A_s_c_t_i_m_e con-
     verts a broken-down time to ASCII and returns a pointer to a
     26-character string.

     The structure declaration from the include file is:

          struct    tm   { /* see ctime(3) */
               short     tm_sec;
               short     tm_min;
               short     tm_hour;
               short     tm_mday;
               short     tm_mon;
               short     tm_year;
               short     tm_wday;
               short     tm_yday;
               short     tm_isdst;
          };

     These quantities give the time on a 24-hour clock, day of
     month (1-31), month of year (0-11), day of week (Sunday =

Printed 7/31/83                                                 1

CTIME(3)            UNIX Programmer's Manual             CTIME(3)

     0), year - 1900, day of year (0-365), and a flag that is
     nonzero if daylight saving time is in effect.

     When local time is called for, the program consults the sys-
     tem to determine the time zone and whether the standard
     U.S.A. daylight saving time adjustment is appropriate.  The
     program knows about the peculiarities of this conversion in
     1974 and 1975; if necessary, a table for these years can be
     extended.

     _T_i_m_e_z_o_n_e returns the name of the time zone associated with
     its first argument, which is measured in minutes westward
     from Greenwich.  If the second argument is 0, the standard
     name is used, otherwise the Daylight Saving version.  If the
     required name does not appear in a table built into the rou-
     tine, the difference from GMT is produced; e.g.  in Afghan-
     istan _t_i_m_e_z_o_n_e(-(_6_0*_4+_3_0), _0) is appropriate because it is
     4:30 ahead of GMT and the string GMT+4:30 is produced.

SEE ALSO
     time(2)

BUGS
     The return values point to static data whose contents are
     overwritten by each call.

Printed 7/31/83                                                 2