4.3BSD - /usr/man/cat3/localtime.0

CTIME(3)                                                              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
       Ctime converts a time pointed to by clock such as returned  by  time(2)
       into  ASCII  and returns a pointer to a 26-character string in the fol‐
       lowing form.  All the fields have constant width.

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

       Localtime and gmtime return pointers to structures containing the  bro‐
       ken-down  time.  Localtime corrects for the time zone and possible day‐
       light savings time; gmtime converts directly to GMT, which is the  time
       UNIX  uses.  Asctime converts 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  system  to
       determine  the  time  zone  and whether the U.S.A., Australian, Eastern
       European, Middle European, or Western  European  daylight  saving  time
       adjustment  is appropriate.  The program knows about various peculiari‐
       ties in time conversion over the past 10-20 years; if  necessary,  this
       understanding can be extended.

       Timezone  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  routine,  the  difference  from  GMT  is  produced; e.g., in
       Afghanistan timezone(-(60*4+30), 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.


4th Berkeley Distribution        May 27, 1986                         CTIME(3)