date_timestamp_get(object)

<?php
   date = date_create("25-09-1989, 07:32:41 GMT");timestamp = date_timestamp_get(date);
   print("Timestamp: ".timestamp);
?>

Timestamp: 622711961

<?php
   date = date_create();timestamp = date_timestamp_get(date);
   print("Timestamp: ".timestamp);
?>

Timestamp: 1589179558

<?php
   //Creating a DateTime object
   date = date_create("25-09-1989");
   //Adding interval to the datenew_date = date_add(date, new DateInterval('PT10H30S'));timestamp = date_timestamp_get(new_date);        print("Timestamp:timestamp");
?>

Timestamp: 622720830

<?php
   date = date_create("1952-04-27");timestamp = date_timestamp_get(date);    print(timestamp);   
?>

-557971200