What is the max year for mktime?

shelbytll

hi,
i wonder what is the max year when using mktime()? Coz when i try to put 2040 for year, it seems to have an error. Did anyone has the same prob?

Weedpacket

Unix-style timestamps (such as those generated by mktime) are good only up until January 18, 2038.

shelbytll

so what happen after year 2038? is it going to be stuck at 2038 forever?

stolzyboy

i think by that time, something will be figured out, i wouldn't worry about it

Weedpacket

It'll roll around and start again at January 1, 1970.

Like stolzyboy says, things should be dealt with by then: 64-bit processors, or just implementing the timestamp as an unsigned long would do the trick, allowing the timestamp to be valid from 1970 until long after the Universe is twice as old as it is now.

'Course, if it's not dealt with, it could represent the sort of threat that the Y2K bug was hyped to be...

shelbytll

So that mean if i were to implement a 50 years license, i can't use the mktime() now....

Weedpacket

Basically. If the database you're using has its own date/time types, look to see if they can handle dates post-2037 (some store dates and times internally as Unix timestamps anyway). If they can, use them to store the date, and the database system's own date/time functions to convert to and from the database's internal format as appropriate.

shelbytll

Hi, I'm trying to develop an application that is database independent. Therefore I do not want to depend on database date/time.

Weedpacket

In that case, use a char(10) string, containing the date in YYYY-MM-DD form (obvious extensions to cover times as well). Such strings would sort chronologically (e.g., 2030-09-12 < 2072-11-08), which makes looking to see if one date is before another a pretty trivial task. More complex tasks involving date arithmetic are hairier, but if the most arithmetic you're going to do is "+50 years", there shouldn't be much problem.