diff.c File Reference

#include <stdlib.h>
#include <grass/datetime.h>
#include "math.h"

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Functions
int	datetime_difference (const DateTime *a, const DateTime *b, DateTime *result)
	This performs the formula: result = a - b;. More...

Function Documentation

int datetime_difference	(	const DateTime *	a,
		const DateTime *	b,
		DateTime *	result
	)

This performs the formula: result = a - b;.

• both a and b must be absolute.
• result will be relative
• If a is "earlier" than b, then result will be set negative.
• b must be no more "precise" than a. (a copy of b is "extended" to the precision of a)
• If result.to == SECOND, then result.fracsec is a.fracsec
• result will have the following from/to based on a.to: result a.to from to YEAR YEAR YEAR MONTH YEAR MONTH DAY DAY DAY HOUR DAY HOUR MINUTE DAY MINUTE SECOND DAY SECOND [LAYOUT ??? - see HTML]
• If either 'a' or 'b' has a timezone, both must have a timezone. The difference will account for the differences in the time zones.

Parameters

a
b
result

Returns

int

Definition at line 81 of file diff.c.

References datetime_change_from_to(), datetime_change_to_utc(), datetime_copy(), datetime_error(), datetime_get_timezone(), datetime_in_interval_year_month(), datetime_increment(), datetime_invert_sign(), datetime_set_increment_type(), and datetime_set_type().

Referenced by datetime_get_local_timezone().