PHP Converting milliseconds to date fails for specific millisecond (1425318722000)

So I'm trying to convert milliseconds to date in PHP and I thought the script I had was working fine but getting odd behaviour for a specific millisecond value (1425318722000).

I've checked this across a few websites and all come back with a valid value...

Monday, March 2, 2015 5:52:02 PM GMT

Mon Mar 02 2015 17:52:02

Mon Mar 02 2015 17:52:02 GMT+0000 (GMT)

Mon, 02 Mar 2015 17:52:02 GMT

Any idea why this occurs, is it a PHP bug perhaps?

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318721999/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:01"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722000/1000));"
bool(false)

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722001/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:02"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722002/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:02"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722003/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:02"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722004/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:02"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

php -r "var_dump(DateTime::createFromFormat('U.u', 1425318722005/1000));"
object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2015-03-02 17:52:02"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

Solution

It's the fact that you're using the 'U.u' mask, but the .u is lost from the value when the result is all 0s after the decimal for that division

for($ms = 1425318721999; $ms <= 1425318722001; ++$ms) {
    var_dump(DateTime::createFromFormat('U.u', sprintf('%14.3f', $ms/1000)));
}

Will work, because you're using sprintf() to force those zeroes to be retained after the decimal point

for($ms = 1425318721999; $ms <= 1425318722001; ++$ms) {
    var_dump(DateTime::createFromFormat('U', floor($ms/1000)));
}

would also work, but you'd lose the milliseconds precision

By way of some explanation:

public static DateTime DateTime::createFromFormat ( string $format , string $time [, DateTimeZone $timezone ] )

the createFromFormat() expects a string as the second argument, so PHP is loose casting the result of your division to a string, and a float value like 1425318722.000 will be cast to a string of "1425318722" with no decimal point or following zeroes, so it doesn't conform with the U.u mask which requires the decimal point and following digits