TIMES.C

/* TIMES.C illustrates various time and date functions including: *      time            _ftime          ctime       asctime *      localtime       gmtime          mktime      _tzset *      _strtime        _strdate        strftime * * Also the global variable: *      _tzname */#include <time.h>#include <stdio.h>#include <sys/types.h>#include <sys/timeb.h>#include <string.h>void main(){    char tmpbuf[128], ampm[] = "AM";    time_t ltime;    struct _timeb tstruct;    struct tm *today, *gmt, xmas = { 0, 0, 12, 25, 11, 93 };    /* Set time zone from TZ environment variable. If TZ is not set,     * the operating system is queried to obtain the default value      * for the variable.      */    _tzset();    /* Display operating system-style date and time. */    _strtime( tmpbuf );    printf( "OS time:\t\t\t\t%s\n", tmpbuf );    _strdate( tmpbuf );    printf( "OS date:\t\t\t\t%s\n", tmpbuf );    /* Get UNIX-style time and display as number and string. */    time( <ime );    printf( "Time in seconds since UTC 1/1/70:\t%ld\n", ltime );    printf( "UNIX time and date:\t\t\t%s", ctime( <ime ) );    /* Display UTC. */    gmt = gmtime( <ime );    printf( "Coordinated universal time:\t\t%s", asctime( gmt ) );    /* Convert to time structure and adjust for PM if necessary. */    today = localtime( <ime );    if( today->tm_hour > 12 )    {   strcpy( ampm, "PM" );   today->tm_hour -= 12;    }    if( today->tm_hour == 0 )  /* Adjust if midnight hour. */   today->tm_hour = 12;    /* Note how pointer addition is used to skip the first 11      * characters and printf is used to trim off terminating      * characters.     */    printf( "12-hour time:\t\t\t\t%.8s %s\n",       asctime( today ) + 11, ampm );    /* Print additional time information. */    _ftime( &tstruct );    printf( "Plus milliseconds:\t\t\t%u\n", tstruct.millitm );    printf( "Zone difference in seconds from UTC:\t%u\n",              tstruct.timezone );    printf( "Time zone name:\t\t\t\t%s\n", _tzname[0] );    printf( "Daylight savings:\t\t\t%s\n",              tstruct.dstflag ? "YES" : "NO" );    /* Make time for noon on Christmas, 1993. */    if( mktime( &xmas ) != (time_t)-1 )   printf( "Christmas\t\t\t\t%s\n", asctime( &xmas ) );    /* Use time structure to build a customized time string. */    today = localtime( <ime );    /* Use strftime to build a customized time string. */    strftime( tmpbuf, 128,         "Today is %A, day %d of %B in the year %Y.\n", today );    printf( tmpbuf );}

Output

OS time:                                21:51:03OS date:                                05/03/94Time in seconds since UTC 1/1/70:       768027063UNIX time and date:                     Tue May 03 21:51:03 1994Coordinated universal time:             Wed May 04 04:51:03 199412-hour time:                           09:51:03 PMPlus milliseconds:                      279Zone difference in seconds from UTC:    480Time zone name:                         Daylight savings:                       YESChristmas                               Sat Dec 25 12:00:00 1993Today is Tuesday, day 03 of May in the year 1994.