从Regional Datetime字符串获取日期

I want to fetch only date: 2013-09-24 from the following string using php:

$2013-09-24T11:53:58+02:00am09pam53119_Tue, 24 Sep 2013 11:53:58 +0200Europe/Berlin58000000Tuesday30[0]

I am getting above string from this line of code:

 $second_date =  date('$first_date[0]', strtotime("+15 days") );

Is there any php built-in function to do this or what can be the simplest way?

If you have that weird string, then just use this

<?php    

$str = "$2013-09-24T11:53:58+02:00am09pam53119_Tue, 24 Sep 2013 11:53:58 +0200Europe/Berlin58000000Tuesday30[0]";
$pattern = '/[0-9]{4}-[0-9]{2}-[0-9]{2}/';
preg_match($pattern, $str, $matches);

?>

Use DateTime class. You can even fetch time and timezone :

$str = "$2013-09-24T11:53:58+02:00am09pam531.....";
$dt = new DateTime(substr($str, 1, 25));

echo $dt->format('Y-m-d');
# 2013-09-24

print_r($dt);
/*
DateTime Object
(
    [date] => 2013-09-24 11:53:58
    [timezone_type] => 1
    [timezone] => +02:00
)
*/