4.3BSD-UWisc/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 {
               int tm_sec;    /* 0-59  seconds */
               int tm_min;    /* 0-59  minutes */
               int tm_hour;   /* 0-23  hour */
               int tm_mday;   /* 1-31  day of month */
               int tm_mon;    /* 0-11  month */
               int tm_year;   /* 0-    year - 1900 */
               int tm_wday;   /* 0-6   day of week (Sunday = 0) */
               int tm_yday;   /* 0-365 day of year */
               int tm_isdst;  /* flag: daylight savings time in effect */
          };

     When local time is called for, the program consults the sys-
     tem to determine the time zone and whether the U.S.A.,



Printed 12/27/86          May 27, 1986                          1






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



     Australian, Eastern European, Middle European, or Western
     European daylight saving time adjustment is appropriate.
     The program knows about various peculiarities in time
     conversion over the past 10-20 years; if necessary, this
     understanding 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
     gettimeofday(2), time(3)

BUGS
     The return values point to static data whose content is
     overwritten by each call.


































Printed 12/27/86          May 27, 1986                          2