How do you explain the result for a new DateTime('0000-00-00 00:00:00')?

Question 1

Here is a test code:

<?php

ini_set('date.timezone', 'Europe/London');    
$dt = new DateTime('0000-00-00 00:00:00');

var_dump($dt);

This provides:

object(DateTime)[1]
  public 'date' => string '-0001-11-30 00:00:00' (length=20)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Europe/London' (length=13)

Whereas this is not a valid date. I don't understand the returned value, especially the month... can you explain?

Question 2

You are seeing two effects here. The first one is that you use a way of writing for a date that can be written in multiple forms:

0000-01-01 same as  0000-01-01
0000-01-00 same as -0001-12-31
0000-00-01 same as -0001-12-01
0000-00-00 same as -0001-11-30

So by the date itself, you already specify the 30th November -1.

Now there's the time offset left that differs about the 9 minutes and 21 seconds. That is because of a change in the clock compared to UTC in Paris/France that happened 10 Mar 1911 23:51:38/39 local time.

I modified your code example a bit and introduced the Europe/Paris setting as you have it, which is playing a role. This code is telling as well the offset in seconds from UTC (Z) which is what you're looking for:

$dt = new DateTime('0000-00-00 00:00:00', new DateTimeZone('Europe/Paris'));
printf("%s secs offset from UTCn", $dt->format('r T (e) Z'));

I changed the dates a bit

Fri, 10 Mar 1911 23:51:38 +0009 PMT (Europe/Paris) 561 secs offset from UTC
                                                   ^^^

One second later:

Fri, 10 Mar 1911 23:51:39 +0000 WET (Europe/Paris) 0 secs offset from UTC

When local standard time was about to reach Saturday, 11 March 1911, 00:01:00 clocks were turned backward 0:09:21 hours to Friday, 10 March 1911, 23:51:39 local standard time instead.

That are 561 Secs. Reference: Clock changes in Paris - Time change dates in 1911 and Time zone changes and daylight saving time start/end dates between year 1900 and 1924.

Question 3

I'm not sure what format you're looking for in your difference but here's how to do it using DateTime

$datetime1 = new DateTime();
$datetime2 = new DateTime('2011-01-03 17:13:00');
$interval = $datetime1->diff($datetime2);
$elapsed = $interval->format('%y years %m months %a days %h hours %i minutes %s seconds');
echo $elapsed;

Question 4

The behavior is correct. Both date intervals represent same number of days (364). The month and date part represent the period that needs to be added to/subtracted from first date to reach second date:

1981-11-20 minus 1980-11-21 represents an interval of 11 month 30 day
1980-11-21 + 11 month = 1981-10-21
1981-10-21 + 30 day   = 1981-10-21

1980-11-21 minus 1981-11-20 represents an interval of 11 month 29 day
1981-11-20 - 11 month = 1980-12-20
1980-12-20 - 29 day   = 1980-11-21

A simpler example would be Oct 21 ... Dec 20:

You need to add 1 month 29 days to Oct 21 to reach Dec 20 (note that month before Dec has 30 days)
But ... you need to subtract 1 month 30 days from Dec 20 to reach Oct 21. Oct itself has 31 days which explains the difference.

Question 5

Based on the documentation (Please see Constructing the Signature String section), the parameters passed to string to sign must be URL decoded. From the link:

To construct the signature string of a shared access signature, first construct the string-to-sign from the fields comprising the request, then encode the string as UTF-8 and compute the signature using the HMAC-SHA256 algorithm. Note that fields included in the string-to-sign must be URL-decoded.

Please use un-encoded parameter values in your string to sign and that should fix the problem.

Question 6

My original aim was to have an XML file external to the SWF that my client could maintain themselves, and thus they would have control over the images displayed.

The first answer I posted was not quite the solution I was after: using fx:XML means that the contents of the XML file is actually compiled into the SWF, and hence is not alterable after compilation.

So I've implemented James' solution.

The XML file looks like this:

<?xml version="1.0" encoding="ISO-8859-1"?>

<images>
    <image source="path/to/image1.jpg" />
    <image source="path/to/image2.jpg" />
    <image source="path/to/image3.jpg" />
    <image source="path/to/image4.jpg" />
</images>

MXML:

<?xml version="1.0" encoding="utf-8"?>

<s:Group
    xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:s="library://ns.adobe.com/flex/spark"
    xmlns:mx="library://ns.adobe.com/flex/halo"
    >

    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;

            protected function lstImages_creationCompleteHandler(event : FlexEvent) : void
            {
                dpHttpService.send();
            }

        ]]>

    </fx:Script>

    <fx:Declarations>

        <mx:HTTPService
            id="dpHttpService"
            url="images.xml"
        />

    </fx:Declarations>

    <s:List
        id="lstImages"
        dataProvider="{dpHttpService.lastResult.images.image}"
        width="100%"
        itemRenderer="path.to.render.ImageRenderer"
        skinClass="path.to.skins.ListSkin"
        >

        <s:layout>
            <s:HorizontalLayout gap="2" />
        </s:layout>

    </s:List>

</s:Group>

And in the image renderer, I refer to the data like this:

<mx:Image
    id="imgRendered"
    source="{data.source}"
/>

The really useful thing about this solution is that I can also put full http:// references to images that exist on another site if I want to (remembering crossdomain.xml, of course).

In fact, the images.xml file can exist on another server.

How do you explain the result for a new DateTime('0000-00-00 00:00:00')?

Answers

php,datetime,date

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