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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c++,comp.lang.c
Subject: Re: "C++: Size Matters in Platform Compatibility"
Date: Sun, 18 Aug 2019 14:49:40 -0700
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Geoff <geoff@invalid.invalid> writes:
> On Sun, 18 Aug 2019 12:32:18 +0200, David Brown
> <david.brown@hesbynett.no> wrote:
>
>>> The UNIX epoch-based 64-bit time is good only if you believe the sun
>>> will only last another 2.147 billion years.
>>
>>292 billion years, by my counting.  By that time, any issues with 
>>rollover will be an SEP¹.
>
> Where are you getting that? time_t is the number of seconds since
> January 1, 1970, 0:00 UTC and as a 64-bit integer that's not 292
> billion years.

Yes, it is.  A signed 64-bit time_t has a maximum value of 2**63-1.
2**63-1 seconds is just over 292 billion years.

The GNU coreutils "date" command gives an out of range error
for dates past Dec 31 in the year 2147485547, but that's not a
time_t issue.  Similarly, the type struct tm has tm_year as an int,
which imposes the same limit on systems where int is 32 bits.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */