Parsing strings for date time information:
<?php
$dt = new DateTime("2018-03-08 08:43:57");
?>
This function will not return the timestamp as an integer, but
instead returns a DateTime object, which you can access (as string)
through:
<?php
$dt = new DateTime("2018-03-08 08:44:12");
echo $dt->format( 'U' ), "\n";
?>
Output
1520498652
The DateTime class is what you can do the really cool things
with.