created at time to number php

PHP
$today = date("F j, Y, g:i a");   // October 30, 2019, 10:42 pm
$today = date("D M j G:i:s T Y"); // Wed Oct 30 22:42:18 UTC 2019
$today = date("Y-m-d H:i:s");     // 2019-10-30 22:42:18(MySQL DATETIME format)date("Y-n-j G:i:s");
//-->2020-10-29 23:27:15<?php
$str = 'Tue Dec 15 2009';
$timestamp = strtotime($str);
echo $timestamp;
//output: 1260831600
?>
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