On 16/11/2004, at 7:05 AM, Ryan wrote:
I would like to find out the 'official' way to handle dates in PHP. I am
aware of the limits on a Unix timestamp, but I am writing a financial
application that needs to deal with dates both before 1970 and after 2038
and of course have run into problems when trying to format those dates using
the date() and strftime() functions. This of course then also impacts
Smarty as Smarty's date_format modifier is just a wrapper around strftime().
End of the day, you need to choose something which works for you. There's no right answer, but there's some good answers :)
I store everything in GMT. If I need to know more about the timezone of the object, I'll either store the local time, or the offset from GMT. I choose to store everything as a MySQL DATETIME (YYYY-MM-DD HH:II:SS), because it's human readable, easy to convert to a unix stamp, and more portable across platforms (eg Windows), although it does use a few extra bytes.
It's also important to note that (at least for Unix) Unix timestamps do work pre-1970... they are just a negative integer, so you need to allow for signed integers in your database if that's the format you choose to use.
I've spent a lot of time working with dates and times, trying to understand it all and come up with a solid process. You need to really read the manuals and understand what you're storing, and what you're doing with functions like date() which assumes a GMT stamp, but outputs a TZ-corrected date.
I am looking at the PEAR Date module and that seems to resolve these issues,
but I would like to know if that is the standard/official way to handle
dates in PHP applications as in my application, I would like to have one
handler for dates, rather than separate code for dates within the Unix
timestamp range and for dates outside - so if I switch to PEAR Date, I will
use it everywhere in my code since I cannot take any chance of using date()
or strftime() and possibly getting invalid data.
I've never worked with the PEAR modules, but my recommendation is this:
- store everything as GMT, and store an offset if needed, and understand what it is you're storing
- transport your dates in your scripts as GMT as long as possible (this is what date() and strftime() expect anyway)
- understand when you want to use date(), and when you really want gmdate()
- write some wrapper functions which you understand implicitly, so that you can deal with your data in a way which makes sense to you
The catch here is if you use Windows for either development or production. I have zero experience with this platform, and don't know how much of my knowledge applies in that situation.
Feel free to ask a detailed question to get a detailed answer :)
Justin
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