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Posted by Brandon on 01/22/07 08:13
> >There's an "underlying" storage for dates? I wasn't aware that PHP had
> >a true date type for a timestamp for "lie under."
>
> It doesn't need a *TRUE* date type, it just needs some way to store
> dates (and for the date library functions to use as input and
> output). And a 32-bit integer is pretty lame nowadays. And that
> seems to be what PHP uses for the date library functions (on 32-bit
> machines, anyway).
All I wanted to know was whether I was missing a set of functions that
deal with a true date type (something that stores the parts of a date
separately and takes timezones into account) or if integer timestamps
were all that PHP provides functions for right now.
By the way, integer timestamps are definitely not 32-bits. If they
were, timestamps would have overflowed in less than two months. Any
place I've seen them in a typed language (C/C++, Java, etc.), they have
been 64-bit "long" integers.
> >Timestamps are just
> >integers.
>
> This is not true in general, unless you're saying that "all bits
> is just bits" and trinary is impossible. For example, in MySQL, a
> timestamp has pieces year, month, day, hour, minute, and second.
> In MS-DOS, a file timestamp also had these fields, but the number
> of seconds was missing a bit so only even seconds were possible,
> and the range of years were very limited. And some programs just
> store dates as strings, with or without a time zone.
It sounds like you might be using the word "timestamp" in a much more
general way but a true timestamp is, by definition, just a long integer
representing the time since Jan 1, 1970 Greenwich Mean Time. What you
are describing are other representations of a date/time, which is
exactly what I am after.
In fact, since you mentioned MySQL, the "timestamp" type in MySQL 4.1+
is ACTUALLY a "datetime" object, which is a more complex representation
of a date and time including a timezone. Prior to version 4.1, MySQL's
timestamp type was actually a true POSIX timestamp - all you got back
from a query was a number.
> >I was just hoping that PHP would have something
> >built in for storing dates in a format other than timestamps.
>
> I consider "something built in for storing dates in a format" to
> *BE* a timestamp by definition, even if it's not a POSIX timestamp.
So are you saying that there IS an alternative in PHP? Because so far,
I haven't found one. Just look at the documentation at PHP.net and
look at the example I gave.
$timeStr = "2005-04-06 15:43:34";
$time = strtotime($timeStr);
print date('Y-m-d \a\t H:i', $time)."\n";
$timeStr is just a plain old string and strtotime() parses it into a
POSIX timestamp, which is then passed around to wherever it needs to go
and most of PHP's functions take UNIX timestamps.
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