unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (4.2BSD)
Page:
Section:
Apropos / Subsearch:
optional field

CTIME(3)                   Library Functions Manual                   CTIME(3)



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

SYNOPSIS
       char *ctime(clock)
       long *clock;

       #include <&lt;sys/time.h>&gt;

       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;
                   int  tm_min;
                   int  tm_hour;
                   int  tm_mday;
                   int  tm_mon;
                   int  tm_year;
                   int  tm_wday;
                   int  tm_yday;
                   int  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 = 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 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        26 June 1983                         CTIME(3)