mktime()'s is_dst deprecated, but needed?

Hi all,

(first time I send an email here, so please be forgiving if something
doesn't follow expected rules.)

My web application allows users to enter time stamps (date and time)
given as local times. The time stamp is to be stored as UTC into the
data base.

Since we have summer and winter times (dst) there's an hour in the
autumn which exists twice in local time (it's 2:00 - 3:00 at the last
sunday in october here). Only the user knows which of these two hour is
intended to be stored into the data base, no program ever can decide
that by itself. Thus, the user has to add a character to the supplied
time stamp.

E.g.
"<last sunday in october>, 02:30 A" is summer time (e.g. GMT +02:00),
"<last sunday in october>, 02:30 B" is winter time (e.g. GMT +01:00).

My php function used the "is_dst" parameter of mktime() responding to
the user given "A" or "B".

How's that to solve in the future if "is_dst" doesn't exist any more?
(For now, it still works but gives a log line everytime the function is
called - E_STRICT is set).

Thanks for your help,

Zora

Zora wrote:
> Hi all,
>
> (first time I send an email here, so please be forgiving if something
> doesn't follow expected rules.)
>
> My web application allows users to enter time stamps (date and time)
> given as local times. The time stamp is to be stored as UTC into the
> data base.
>
> Since we have summer and winter times (dst) there's an hour in the
> autumn which exists twice in local time (it's 2:00 - 3:00 at the last
> sunday in october here). Only the user knows which of these two hour is
> intended to be stored into the data base, no program ever can decide
> that by itself. Thus, the user has to add a character to the supplied
> time stamp.
>
> E.g.
> "<last sunday in october>, 02:30 A" is summer time (e.g. GMT +02:00),
> "<last sunday in october>, 02:30 B" is winter time (e.g. GMT +01:00).
>
> My php function used the "is_dst" parameter of mktime() responding to
> the user given "A" or "B".
>
> How's that to solve in the future if "is_dst" doesn't exist any more?
> (For now, it still works but gives a log line everytime the function is
> called - E_STRICT is set).
>
> Thanks for your help,
>
> Zora
>
> --------------010002030701000104070607--

Since you're getting that error I'll assume you're using PHP 5.1 or
higher. UTC has no concept of DST, so what you really want to be using
are strtotime() and date_default_timezone_set(). Here's the idea:

$someString = '10/16/2006 5:37 pm'; //this is a string
date_default_timezone_set('American/New_York'); //this is the user's
timezone. It will determine how the string is turned into UTC

$timestamp = strtotime($someString); //$timestamp now has UTC
equivalent of 10/16/2006 5:37 pm in New York
echo date('Y/m/d H:i:s', $timestamp); //prints out the nicely formatted
version of that timestamp, as if you were in New York

date_default_timezone_set('American/Los_Angeles');
echo date('Y/m/d H:i:s', $timestamp); //prints out the nicely formatted
version of that timestamp, as if you were in LA -- takes care of the
conversion and everything

So, setting the timezone then using strtotime() and date() takes care
of all the DST/non-DST stuff, converting between timezones, etc.

On Sun, 15 Oct 2006 13:22:02 +0200, Zora wrote:

> Hi all,
>
> (first time I send an email here, so please be forgiving if something
> doesn't follow expected rules.)
>
> My web application allows users to enter time stamps (date and time)
> given as local times. The time stamp is to be stored as UTC into the
> data base.
>
> Since we have summer and winter times (dst) there's an hour in the
> autumn which exists twice in local time (it's 2:00 - 3:00 at the last
> sunday in october here). Only the user knows which of these two hour is
> intended to be stored into the data base, no program ever can decide
> that by itself. Thus, the user has to add a character to the supplied
> time stamp.
>
> E.g.
> "<last sunday in october>, 02:30 A" is summer time (e.g. GMT +02:00),
> "<last sunday in october>, 02:30 B" is winter time (e.g. GMT +01:00).
>
> My php function used the "is_dst" parameter of mktime() responding to
> the user given "A" or "B".
>
> How's that to solve in the future if "is_dst" doesn't exist any more?
> (For now, it still works but gives a log line everytime the function is
> called - E_STRICT is set).
>
> Thanks for your help,
>
> Zora

Hi Zora,

How is the data stored in the database? By the timestamp of your
local time? In that case, you could just increment the timestamp by one
hour if someone sets summertime. You can also feed the mktime the
incremented hour, cause it will calculate the time correctly even with
values that are out of range (such as 25 hours, 75 minutes, etc).

Hope this helps,

Ivo