DateTime::createFromFormat with timezone does change output

Question

Regardless, of what timezone I feed in, I get same result.

I expected time fed into (2nd argument) to be UTC - it does not seem to be.

In such case, what is the use of third argument - timezone, if we do not get time in selected timezone, but repetition of time we fed into?

I see offset (in parentheses), but fail to understand, how is that practically useful.

I appreciate, if someone would explain, what I do not get here right.

When I use:

DateTime::createFromFormat("Y-m-d H:i:s", "2019-05-31 10:00:56", new DateTimeZone('America/Fortaleza'));

I get this:

DateTime @1559307656 {#1978
  date: 2019-05-31 10:00:56.0 America/Fortaleza (-03:00),
}

I expected to get:

DateTime @1559307656 {#1978
  date: 2019-05-31 07:00:56.0 America/Fortaleza (-03:00),
}

Actually, I do not get any change, regardless of timezone fed in:

>>> DateTime::createFromFormat("Y-m-d H:i:s", "2019-05-31 10:00:56", new DateTimeZone('UTC'))
DateTime @1559296856 {#1979
  date: 2019-05-31 10:00:56.0 UTC (+00:00),
}

>>> DateTime::createFromFormat("Y-m-d H:i:s", "2019-05-31 10:00:56", new DateTimeZone('Europe/Moscow'))
DateTime @1559286056 {#1958
  date: 2019-05-31 10:00:56.0 Europe/Moscow (+03:00),
}

Answer 1

You're misunderstanding the use of the third parameter. It is used to tell DateTime::createFromFormat what the timezone of the time you have passed in is, which also becomes the timezone of the result. If your input time is UTC , that is the appropriate value for the third parameter, and you can then use DateTime::setTimeZone to set the timezone of the value:

$date = DateTime::createFromFormat("Y-m-d H:i:s", "2019-05-31 10:00:56", new DateTimeZone('UTC'));
$date->setTimeZone(new DateTimeZone('America/Fortaleza'));
var_dump($date);

Output:

object(DateTime)#2 (3) {
  ["date"]=> string(26) "2019-05-31 07:00:56.000000"
  ["timezone_type"]=> int(3)
  ["timezone"]=> string(17) "America/Fortaleza" 
}

Demo on 3v4l.org