Things about date in php.

date.php

<?php

// PRC looks like '爬入场';
// Hoho~
date_default_timezone_set('PRC');

var_dump(DateTime::createFromFormat('Ymd', '20130229'));

/*
Result:

object(DateTime)#1 (3) {
  ["date"]=>
  string(19) "2013-03-01 17:24:27"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(3) "PRC"
}

*/

var_dump(stringtotime('20130229');

/*
Result:

int(1362067200)

*/

var_dump(date('Ymd', strtotime('-1 month', strtotime('20130328'))));

/*
Result:

string(8) "20130228"

*/