Re: Noooooo... (localtime in Unix98)

[Dominic Dunlop <domo@computer.org>]

At 11:12 +0100 2000-01-04, Bart Schuller wrote:
>This piece of the RISKS digest caught my eye. The "open"software website
>won't let me in to check, unfortunately.

After jumping through a number of tedious hoops, it is possible for 
non-members to get on-line access to standards at 
<http://www.opengroup.org>.  Belatedly, I've got around to doing this.

 From RISKS:
>The UNIX98 standard
>changed the localtime() function so that the year value is redefined to
>be the "year in the current century" rather than "years since 1900".

Not true:

 From UNIX98 localtime():

#include <time.h>

struct tm *localtime(const time_t *timer);

 From UNIX98 time.h:

The <time.h> header declares the structure tm, which includes at 
least the following members:

int    tm_sec   seconds [0,61]
int    tm_min   minutes [0,59]
int    tm_hour  hour [0,23]
int    tm_mday  day of month [1,31]
int    tm_mon   month of year [0,11]
int    tm_year  years since 1900
int    tm_wday  day of week [0,6] (Sunday = 0)
int    tm_yday  day of year [0,365]
int    tm_isdst daylight savings flag

At 17:29 +0000 2000-01-04, M.J.T. Guy wrote:
>I don't know anything about UNIX98, but this looks like typical FUD
>to me.    Any system that defines localtime() like (or to be pedantic,
>struct tm) is in violation of ANSI C.     So I don't believe it.

Justifiably.  The only wrinkle is that a conforming implementation is 
allowed to add fields giving century number and year in century if it 
wants.  Hell, it can add a field giving the phase of the moon if it 
wants -- useful for bug-hunting.  So maybe somebody's done that. 
But, if they have, we can ignore it.

-- 
Dominic Dunlop

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Follow-Ups from:

Bennett Todd <bet@rahul.net>

References to:

Bart Schuller <schuller@lunatech.com>

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