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