68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
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/*
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* gmtime.c
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* Original Author: G. Haley
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*
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* Converts the calendar time pointed to by tim_p into a broken-down time
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* expressed as Greenwich Mean Time (GMT). Returns a pointer to a structure
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* containing the broken-down time, or a null pointer if GMT is not
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* available.
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*/
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/*
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FUNCTION
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<<gmtime>>---convert time to UTC traditional form
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INDEX
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gmtime
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ANSI_SYNOPSIS
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#include <time.h>
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struct tm *gmtime(const time_t *<[clock]>);
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struct tm *gmtime_r(const time_t *<[clock]>, struct tm *<[res]>);
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TRAD_SYNOPSIS
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#include <time.h>
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struct tm *gmtime(<[clock]>)
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const time_t *<[clock]>;
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struct tm *gmtime_r(<[clock]>, <[res]>)
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const time_t *<[clock]>;
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struct tm *<[res]>;
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DESCRIPTION
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<<gmtime>> assumes the time at <[clock]> represents a local time.
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<<gmtime>> converts it to UTC (Universal Coordinated Time, also known in some
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countries as GMT, Greenwich Mean time), then converts the
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representation from the arithmetic representation to
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the traditional representation defined by <<struct tm>>.
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<<gmtime>> constructs the traditional time representation in static
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storage; each call to <<gmtime>> or <<localtime>> will overwrite the
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information generated by previous calls to either function.
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RETURNS
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A pointer to the traditional time representation (<<struct tm>>).
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PORTABILITY
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ANSI C requires <<gmtime>>.
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<<gmtime>> requires no supporting OS subroutines.
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*/
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#include <stdlib.h>
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#include <time.h>
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#define _GMT_OFFSET 0
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#ifndef _REENT_ONLY
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struct tm *
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_DEFUN (gmtime, (tim_p),
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_CONST time_t * tim_p)
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{
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time_t tim = *tim_p + _GMT_OFFSET;
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return (localtime (&tim));
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}
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#endif
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