A representation of time zone information.
Syntax
#include <prtime.h> typedef struct PRTimeParameters { PRInt32 tp_gmt_offset; PRInt32 tp_dst_offset; } PRTimeParameters;
Description
Each geographic location has a standard time zone, and if Daylight Saving Time (DST) is practiced, a daylight time zone. The PRTimeParameters
structure represents the local time zone information in terms of the offset (in seconds) from GMT. The overall offset is broken into two components:
tp_gmt_offset
- The offset of the local standard time from GMT.
tp_dst_offset
- If daylight savings time (DST) is in effect, the DST adjustment from the local standard time. This is most commonly 1 hour, but may also be 30 minutes or some other amount. If DST is not in effect, the tp_dst_offset component is 0.
For example, the US Pacific Time Zone has both a standard time zone (Pacific Standard Time, or PST) and a daylight time zone (Pacific Daylight Time, or PDT).
- In PST, the local time is 8 hours behind GMT, so
tp_gmt_offset
is -28800 seconds.tp_dst_offset
is 0, indicating that daylight saving time is not in effect.
- In PDT, the clock is turned forward by one hour, so the local time is 7 hours behind GMT. This is broken down as -8 + 1 hours, so
tp_gmt_offset
is -28800 seconds, andtp_dst_offset
is 3600 seconds.
A second example is Japan, which is 9 hours ahead of GMT. Japan does not use daylight saving time, so the only time zone is Japan Standard Time (JST). In JST tp_gmt_offset
is 32400 seconds, and tp_dst_offset
is 0.