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©Copyright 1996 Rogue Wave Software
#include <time.h>
#include <rw/zone.h> (abstract base class)
RWZone is an abstract base class. It defines an interface for time zone issues such as whether or not daylight-saving time is in use, the names and offsets from UTC (also known as GMT) for both standard and daylight-saving times, and the start and stop dates for daylight-saving time, if used.
Note that because it is an abstract base class, there is no way to actually enforce these goals -- the description here is merely the model of how a class derived from RWZone should act.
Most programs interact with RWZone only by passing an RWZone reference to an RWTime or RWDate member function that expects one.
RWZoneSimple is an implementation of the abstract RWZone interface sufficient to represent U.S. daylight-saving time rules. Three instances of RWZoneSimple are initialized from the global environment at program startup to represent local, standard, and universal time. They are available via calls to the static member functions RWZone::local(), RWZone::standard(), and RWZone::utc(), respectively. See the class RWZoneSimple for details.
None
#include <rw/zone.h>
#include <rw/rwtime.h>
#include <rw/rstream.h>
main(){
RWTime now;
cout << now.asString('\0', RWZone::local()) << endl;
cout << now.asString("%x %X", RWZone::utc()) << endl;
return 0;
}
enum DstRule { NoDST, NoAm, WeEu };
Used by the static member function dstRule(), described below, and by constructors for classes derived from RWZone.
enum StdZone {
NewZealand = -12, CarolineIslands, MarianaIslands,
Japan, China, Java,
Kazakh, Pakistan, CaspianSea,
Ukraine, Nile, Europe,
Greenwich, Azores, Oscar,
Greenland, Atlantic, USEastern,
USCentral, USMountain, USPacific,
Yukon, Hawaii, Bering
};
StdZone is provided to name the standard time zones. Its values are intended to be passed to constructors of classes derived from RWZone.
virtual int timeZoneOffset() const = 0;
Returns the number of seconds west of UTC for standard time in this zone. The number is negative for zones east of Greenwich, England.
virtual int altZoneOffset() const = 0;
Returns the number of seconds west of UTC for daylight-saving time in this zone.
virtual RWBoolean daylightObserved() const = 0;
Returns TRUE if daylight-saving time is observed for this zone.
virtual RWBoolean isDaylight(const struct tm* tspec) const = 0;
Returns TRUE if the time and date represented in the struct tm argument is in the range of daylight-saving time for this zone. The elements of the tm argument must all be self-consistent; in particular, the tm_wday member must agree with the tm_year, tm_mon, and tm_day members.
virtual void getBeginDaylight(struct tm*) const = 0; virtual void getEndDaylight (struct tm*) const = 0;
Return with the struct tm argument set to the local time that daylight-saving time begins, or ends, for the year indicated by the tm_year member passed in. If daylight-saving time is not observed, the struct tm members are all set to a negative value. Note that in the southern hemisphere, daylight-saving time ends at an earlier date than it begins.
virtual RWCString timeZoneName() const = 0; virtual RWCString altZoneName() const = 0;
Return the name of, respectively, the standard and daylight-saving time zones represented, such as "PST" and "PDT". Note that the current date and time have no effect on the return values of these functions.
static const RWZone& local();
Returns a reference to an RWZone representing local time. By default this will be an instance of RWZoneSimple created with offsets and zone names from the operating system, with U.S. rules for daylight-saving time if observed. This is used as the default argument value for RWDate and RWTime functions that take an RWZone.
static const RWZone& standard();
Returns a reference to an RWZone representing standard local time, with no daylight-saving time corrections. By default this is an instance of RWZoneSimple with offset and zone name from the operating system.
static const RWZone& utc();
Returns a reference to an RWZone representing UTC (GMT) universal time.
static const RWZone* local(const RWZone*); static const RWZone* standard(const RWZone*);
These functions allow the values returned by the other functions above to be set. Each returns the previous value.
static constRWDaylightRule* dstRule(DstRule rule = NoAm);
Returns one of the built-in daylight-saving time rules according to rule. Function dstRule() is provided for convenience in constructing RWZoneSimple instances for time zones in which common daylight-saving time rules are obeyed. Currently two such rule systems are provided, NoAm for the U.S.A. and Canada, and WeEu for most of Western Europe (excluding the U.K.). See RWZoneSimple for more details. If DstRule NoDST is given, then 0 is returned. The result of calling dstRule() is normally passed to the RWZoneSimple constructor.
