Convert formatted date back to unix

Question

Which function would I use to convert custom formatted dates back to Unix Epoch time?

For example:

("Ymd") -> ("U");

I looked at date("U",strtotime("20140525")); , but I'm not sure how to fit in the original format Ymd.

How does that function know that the input format is YYYYMMDD, because it looks like it works.

Thanks

Answer 1

You can use DateTime::createFromFormat():

$date = DateTime::createFromFormat('Ymd', '20140525');
echo $date->format('U');