HP Integrity NonStop J-Series - Manual (Page 69)

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©Copyright 1996 Rogue Wave Software
Chapter 5: Using Class RWTime
Setting the Time Zone ❍
Constructors ❍
Member Functions ❍
Class RWTime represents time, stored as the number of seconds since 1 January 1901 UTC.
UTC is sometimes called GMT, for Greenwich Meridian Time. The number of seconds that can
be stored is limited by the size of a long on your system. The last date and time that can be
represented with a four-byte (32-bit) long is 22:28:15 February 5, 2037 UTC.
Class RWTime uses UTC because it is a widely accepted standard, useful in calculations, but it
is not the usual time reference people use in their daily lives. We tell time with a local time
which may or may not observe daylight-saving time (DST) conventions; in fact, DST may or
may not be in effect.
When we create an RWTime object to represent the current time, the library obtains the current
UTC time directly from the operating system. However, when we create an RWTime object for
some specific time, we are unlikely to do so with UTC. More likely, the time we give it will be
with respect to some other time zone, and we must specify which time zone for RWTime to do
its job, or even print out the time. So by default, RWTime uses a global local time, set by
RWZone::local().