Re: Date to epoch

The normal Perl functions cannot handle this year of 2106 because:

On perl versions older than 5.12.0, the range of dates that can be actually be handled depends on the size of time_t (usually a signed 32 bit integer) on the given platform. Currently, this is 32 bits for most systems, yielding an approximate range from Dec 1901 to Jan 2038. This integer is the number of seconds from the "epoch" or arbitrary start time/date (plus or minus).

There are a number of modules on CPAN that can handle dates greater or less than the normal Unix epoch. These are good for internal program calculations.
You might find: UNIX Time interesting.

Since the "epoch" date is arbitrary, I would not use this integer for date/time interchange between systems and I would not assume that the other system uses 64 bits vs 32 bits.

Comment on Re: Date to epoch

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Re^2: Date to epoch by akagrawal3 (Beadle) on Jul 25, 2012 at 10:29 UTC
Oh... Thanks for this info... This might help me in making my concept clear.	[reply]
Re^3: Date to epoch by Marshall (Canon) on Jul 29, 2012 at 22:57 UTC
Instead of a 32 bit int describing the combined year and time, you could make two ints: $year and $time. Or perhaps better: look in CPAN for time/date modules that can describe this concept with a more complex data structures. Doing "date/time" math can be more complex than you might think. For a small example, this year (2012) - we had a "leap second" - WOW - what the heck does that mean?. I didn't mean to make a pun. But think about this and what might happen in 2106?	[reply]
Re^2: Date to epoch by locked_user sundialsvc4 (Abbot) on Jul 19, 2012 at 16:03 UTC
So here we go again ... welcome to the Y2038 problem. That’s only 26 years away now. Plenty of time to say the sky is falling... again. Plenty of time to write the books ... and to make the tin-foil hats. P.S.: I actually collected “Y2K books” at that time, knowing that they’d be gone in an instant ...
Re^3: Date to epoch by Marshall (Canon) on Jul 21, 2012 at 23:43 UTC
from local Time Strictly speaking, the year should be specified in a form consistent with localtime(), i.e. the offset from 1900. In order to make the interpretation of the year easier for humans, however, who are more accustomed to seeing years as two-digit or four-digit values, the following conventions are followed Years greater than 999 are interpreted as being the actual year, rather than the offset from 1900. Thus, 1964 would indicate the year Martin Luther King won the Nobel prize, not the year 3864. Years in the range 100..999 are interpreted as offset from 1900, so that 112 indicates 2012. This rule also applies to years less than zero (but see note below regarding date range). Years in the range 0..99 are interpreted as shorthand for years in the rolling "current century," defined as 50 years on either side of the current year. Thus, today, in 1999, 0 would refer to 2000, and 45 to 2045, but 55 would refer to 1955. Twenty years from now, 55 would instead refer to 2055. This is messy, but matches the way people currently think about two digit dates. Whenever possible, use an absolute four digit year instead. The scheme above allows interpretation of a wide range of dates, particularly if 4-digit years are used. I have a 6 Mhz, pre-production PC with a Quantum "Hard Card" => This is free to "good home". This is a part of the history of the PC. Contact me if you are interested. Computer are faster and have more storage than the Y2K models. Most folks are aware of this issue and use 4 digits for the year and DB's can handle that.	[reply]