Unix time in millisecond to d-m-Y - php-5.2

Question

I'm pulling a unix time in milliseconds from an xml document but can't convert it to a readable date (d-m-Y) in php 5.2.17.
I've used http://www.epochconverter.com/ which converts it correctly
from 1328723926776 to 2/9/2012 13:37:49
I've tried the following:
$timestamp = $xml['LastBackupDate'];
echo '<br />Method 1: '.date("d-m-Y", $timestamp);
echo '<br />Method 2: '.date("d-m-Y", strtotime($timestamp));
echo '<br />Method 3: '.date("d-m-Y", strtotime($timestamp*1000));
echo '<br />Method 4: '.date("d-m-Y", strtotime($timestamp/1000));
echo '<br />Method 5: '.date("d-m-Y", $timestamp/1000);
echo '<br />Method 6: '.date("d-m-Y", (int)$timestamp);
echo '<br />Method 7: '.date("d-m-Y", intval($timestamp));
echo '<br />Method 8: '.date("d-m-Y", intval($timestamp)/1000);
echo '<br />Method 9: '.date("d-m-Y", intval($timestamp/1000));
which brings back:
Method 1:
Method 2: 01-01-1970
Method 3: 01-01-1970
Method 4: 01-01-1970
Method 5: 25-01-1970
Method 6: 19-01-2038
Method 7: 19-01-2038
Method 8: 25-01-1970
Method 9: 25-01-1970
Any ideas how to convert this?
Thanks!
Edit, Best result from using:
echo date("d-m-Y", substr($xml['LastBackupDate'],0,-3));

Answer 1

Have you tried dividing by 1000, instead of multiplying? Epoch time is usually in seconds ...
OK, so now I actually need to learn PHP ...
date takes a format and a time.
strtotime takes a human-readable date/time string and returns a time. Your value is epoch time in milliseconds, not a human-readable string, so isn't a valid argument to strtotime.
Try Method 4 without the strtotime, it shouldn't be needed.
Right, that didn't work, because $timestamp is a string (I'd assumed it was already an integer).
You say that dropping the last 3 characters of the string gets you most of the way, that is the same as converting to an integer and then dividing by 1,000. Your methods 6 & 7 convert to int but don't divide - you need both!
According to this, date requires an integer timestamp in seconds. The value you have is a string, so you should convert it to an integer. It is also in milliseconds, so you have to divide by 1,000 to get the right units.
Note that epoch time is counted as seconds since the first of January, 1970. So, any time you see 01-01-1970, the second argument evaluated to zero.
date("d-m-Y", $timestamp); <-- string, not int: treated as zero
date("d-m-Y", strtotime($timestamp)); <-- not a formatted time, gives zero
date("d-m-Y", strtotime($timestamp*1000)); <-- ditto
date("d-m-Y", strtotime($timestamp/1000)); <-- ditto
date("d-m-Y", $timestamp/1000); <-- clearly nonzero, but no idea what!
date("d-m-Y", (int)$timestamp); <-- correct type but in milliseconds
date("d-m-Y", intval($timestamp)); <-- correct type but in milliseconds
If you pass an integer containing a number of seconds rather than milliseconds, it should be correct.
Like so:
date("d-m-Y", intval($timestamp)/1000);