RWZone(3C++) RWZone(3C++)
NameRWZone - Rogue Wave library class
Synopsis
#include <time.h>
#include <rw/zone.h>
(abstract base class)
DescriptionRWZone 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.
Persistence
None
Example
#include <rw/zone.h>
#include <rw/rwtime.h>
#include <rw/rstream.h>
main(){
RWTime now;
cout << now.asString(' ', RWZone::local()) << endl;
cout << now.asString("%x %X", RWZone::utc()) << endl;
return 0;
}
Enumerations
enum DstRule { NoDST, NoAm, WeEu };
Used by the static member function dstRule(), described below, and by
constructors for classes derived from RWZone.
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RWZone(3C++) RWZone(3C++)
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.
Public Member Functions
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-
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RWZone(3C++) RWZone(3C++)
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 Public Member 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);
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RWZone(3C++) RWZone(3C++)
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.
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