The way that Unix machines tell the time is by counting the number of seconds
that have elapsed since Midnight 1 January 1970. They call this the Unix Epoch.
So if we had a piece of PHP that looked something like this:
it would return to me a result of
This just happens to be about 12h43 on Sunday 21 May 2000.
This is all well and good you may say, but how does that help me ?
Well quite a bit actually. A lot of the functions that do date manipulation in
PHP require the timestamp that is returned by the time() function as one of the
inputs. Also, since PHP uses the timestamp in the same way under both Unix and
Windows, it allows you to use code on either operating system without any
problems. A further bonus is that since the time() function is returning an
integer, you can store it as such in a database or text file - no more need for
fancy date/time database fields.
OK, so now that you have the how and why about Unix timestamps, let's get on to
the really important bits and start using it for something useful.