CalendarTime

CalendarTime Class

CalendarTime class provides instance variables for elements of a broken-down clock and calendar UTC time: seconds, minutes, hours, day of the month, and so on. The methods in this class might be more convenient in many cases than their functional equivalents in CTime class.

All of the methods in this class expect that the receiver has made a previous call to getUTCTime (which is defined in CTime class). The getUTCTime method fills in the receiver’s value with the UTC seconds since the epoch. See CTime.

The localTime and gmTime methods contain calls to the system’s localtime(3) and gmtime(3) library functions (or localtime_r and gmtime_r). These manual pages provide more information about how the system translates seconds since 1900 into a local time zone’s calendar time, or UTC calendar time.

This brief example prints an ISO-format date and time string.

int main () {
  CalendarTime new ct;

  ct utcTime;
  ct localTime;
  printf ("%s\n", ct isoTimeString);
}

Instance Variables

seconds

minutes

hours

dom

month

year

dow

doy

Integers that contain the clock time and calendar date represented by the receiver’s UTC time. The values are translated using the local time zone information if necessary.

Instance Variable                   Range
-----------------                   -----
seconds                             0 - 59
minutes                             0 - 59
hours                               0 - 23
dom  (day of the month)             1 - 31
month                               0 - 11 (0 = January)
year                                Years since 1900.
dow  (day of the week)              0 - 6  (0 = Sunday)
doy  (day of the year)              0 - 365
isdst                               > 0 : true
                                      0 : false
                                    < 0 : not available

isdst

An Integer value that indicates whether Daylight Savings Time is in effect on systems that support it. If the value is positive, Daylight Savings Time is in effect, zero indicates that DST is not in effect, and a value less than zero indicates that the information is not available.

timeZone

An Integer that contains the seconds west of GMT of the local time zone.

tzStd

tzDst

gmtOff

String objects that contain the abbreviation of the standard local time zone, the local daylight savings time zone, and the hours from GMT, usually expressed as a four digit number; e.g., ‘-0700’ for the MST time zone. The value of gmtOff is the result of dividing the value of the timeZone instance variable by -3600, them multiplying the result by 100. The haveDst instance variable is true if the timezone supports daylight savings time, but not all systems support this. To find out whether daylight savings time is in effect, the isdst instance variable above, can provide that information if the machine supports it.

Calling the localTime and zoneInfo methods fill in the time zone information.

Instance Methods

cTimeString (void)

Returns a formatted string with the date and time given by the receiver.

The returned String is formatted similarly to the output of the ctime(3) C function, except that the string does not include a trailing newline.

Programs should call the utcTime method to get the current UTC time, and then either the localTime or gmTime method to convert the UTC time into calendar day and date information, before calling this method.

dayName (void)

Returns a String with the three-letter abbreviation of the current day: ‘Sun’, ‘Mon’, ‘Tue’, ‘Wed’, ‘Thu’, ‘Fri’, and ‘Sat’.

gmTime (void)

Fills in the receiver’s instance variables with the elements of the UTC calendar time.

Programs should call the utcTime method to get the current UTC time before calling this method.

isoTimeString (void)

Returns a formatted string with the date and time given by the receiver. The returned String has the format of an ISO date and time string.

Programs should call the utcTime method to get the current UTC time, and then either the localTime or gmTime methods to convert the UTC time into calendar day and date information, before calling this method.

localTime (void)

Fills in the receiver’s instance variables with the elements of the local calendar time, as determined by the system’s time zone setting.

Programs should call the utcTime method to get the current UTC time before calling this method.

monName (void)

Returns a String with the three-letter abbreviation of the current time’s month: ‘Jan’, ‘Feb’, ‘Mar’, ‘Apr’, ‘May’, ‘Jun’, ‘Jul’, ‘Aug’, ‘Sep’, ‘Oct’, ‘Nov’, and ‘Dec’.

zoneInfo (void)

Fills in the receiver’s timeZone, tzStd, tzDst, gmtOff, and haveDst with information about the machine’s current time zone.