php - convert xml (milliseconds?) to readable date

Question

I have an XML file I am parsing and then inserting into my database using PHP. The date nodes however are in a weird XML format that I believed to be milliseconds. My attempts to convert this so far have been unsuccessful and I was hoping someone could point out my error.

XML

<est__start>1335744000000</est__start>
<est__end>1342742400000</est__end>

Which was this much more readable date before being converted

<est__start> 04-30-2012 </est__start>
<est__end> 07-20-2012 </est__end>

PHP

$start = $data->est__start;
if (empty($start)) {
    $start = '';
} else {
    $start = intval($start);            
    $seconds = $start / 1000;
    $start = date("d-m-Y", $seconds);
}
$end = $data->est__start;
if (empty($end)) {
    $end = '';
} else {
    $end = intval($end);            
    $seconds = $end / 1000;
    $end = date("d-m-Y", $end);
}

The end result however is always something similar to this

25-01-1970

and I need it to look like it did before the conversion. Like this

04-30-2012

Since I'm not handling the original date conversion when it goes into the XML file I'm not sure where I'm going wrong. Any help is appreciated.

Answer 1

PHP uses the string value of the SimpleXMLElement if you use it in intval or as well directly in numeric calculations (which also cast to int).

As I already commented, my first quick guess was right, it truncates the number than to the maximum integer available on a 32 bit system signed (2³¹ − 1) (I guess you're using one) which results in:

2 147 483 647
25-01-1970

This number btw. is sort of somewhat famous and has it's own Wikipedia page: 2147483647.

Instead use the floatval function, it gives you what you're looking for:

$seconds = floatval($start) / 1000;
echo date("d-m-Y", $seconds); # prints "30-04-2012"

Bonus: Here is some code you might find handy to have the conversion code in a central place and easily make use of:

/**
 * Class MySimpleXMLElement
 *
 * Extended SimpleXMLElement
 */
class MySimpleXMLElement extends SimpleXMLElement
{
    /**
     * @param string $format
     *
     * @return bool|string
     */
    public function getDateFromMilliseconds($format = "d-m-Y") {
        return date("d-m-Y", floatval($this) / 1000);
    }

    /**
     * @param DateTimeZone $timezone
     *
     * @return DateTime
     */
    public function createDateTimeFromMilliseconds(DateTimeZone $timezone = NULL) {
        return new DateTime('@' . (floatval($this) / 1000), $timezone);
    }
}

$data  = new MySimpleXMLElement('<r><est__start>1335744000000</est__start><est__end>1342742400000</est__end></r>');
/* @var $start MySimpleXMLElement */
$start = $data->est__start;

echo $start->getDateFromMilliseconds(), "\n"; # prints "30-04-2012"

echo $start->createDateTimeFromMilliseconds()->format('Y-m-d'); # prints "2012-04-30"

It works by extending from SimpleXMLElement and adding the date-creation functions, here one for a formatted string and for more advanced datetime operations one that gives back a DateTime object.

Last time I extended SimpleXMLElement on Stackoverflow was in an answer to the "How to replace XML node with SimpleXMLElement PHP" question.

Answer 2

You're using intval but the numbers are too large for int. Just use:

date("m-d-Y", 1335744000000 / 1000); // 04-30-2012

Answer 3

you are not passing seconds in the second run:

Answer 4

Possible UTC, and switch day and month:

echo gmdate('m-d-Y',1342742400000 / 1000);

Result:

07-20-2012