73 lines
1.6 KiB
Groff
73 lines
1.6 KiB
Groff
.TH datetime 3
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.SH NAME
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datetime \- convert between TAI labels and seconds
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.SH SYNTAX
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.B #include <datetime.h>
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void \fBdatetime_tai\fP(&\fIdt\fR,\fIt\fR);
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datetime_sec \fBdatetime_untai\fP(&\fIdt\fR);
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struct datetime \fIdt\fR;
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.br
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datetime_sec \fIt\fR;
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.SH DESCRIPTION
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International Atomic Time, TAI,
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is the fundamental unit for time measurements.
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TAI has one label for every second of real time,
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without complications such as leap seconds.
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A
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struct datetime
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variable,
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such as
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.IR dt ,
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stores a TAI label.
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.I dt\fB.year
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is the year number minus 1900;
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.I dt\fB.mon
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is the month number, from 0 (January) through 11 (December);
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.I dt\fB.mday
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is the day of the month, from 1 through 31;
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.I dt\fB.hour
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is the hour, from 0 through 23;
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.I dt\fB.min
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is the minute, from 0 through 59;
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.I dt\fB.sec
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is the second, from 0 through 59;
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.I dt\fB.wday
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is the day of the week, from 0 (Sunday) through 6 (Saturday);
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.I dt\fB.yday
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is the day of the year, from 0 through 365.
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The
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.B datetime
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library supports more convenient TAI manipulation with
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the datetime_sec type.
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A datetime_sec value, such as
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.IR t ,
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is an integer referring to the
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.IR t th
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second after the beginning of 1970 TAI.
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The first second of 1970 TAI was 0;
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the next second was 1;
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the last second of 1969 TAI was -1.
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The difference between two datetime_sec values is a number
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of real-time seconds.
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.B datetime_tai
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converts a datetime_sec to a TAI label.
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.B datetime_untai
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reads a TAI label
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(specifically
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.IR dt\fB.year ,
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.IR dt\fB.mon ,
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.IR dt\fB.mday ,
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.IR dt\fB.hour ,
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.IR dt\fB.min ,
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and
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.IR dt\fB.sec )
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and returns a datetime_sec.
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.SH "SEE ALSO"
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now(3)
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