php - strtotime and DateTime giving wrong year when parsing a year -

$year = date('y', strtotime("2012")); var_dump($year);//returns 2013 

this happening old server php 5.2 , new 1 php 5.4

the server uses strtotime year string 2012-01-01 or 2012-01 or 2012

i tried using $dt = new datetime('2012') , gettimestamp returns "1374516720" "mon, 22 jul 2013 18:12:00 gmt"

what causing bug? in documentation says strtotime accepts year

i don't know do...

edit:

$year = date('y', strtotime("2012")); 

gets treated military time, 20:12 current year

using complete date string yyyy-mm-dd , 01.01 day did trick me:

$year = date('y', strtotime("2012-01-01")); var_dump($year);//returns 2012 

normally suggest use datetime::createfromformat() @rufinus suggested, method not available in php5.2 (what using on 1 of servers). maybe reason fro upgrading old one? ;)

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reasons why happens:

while manual says @ 1 point yyyy (and yyyy) formats ok, tells restrictions behaviour lines below: strtotime() called yyyy under special circumstances return time stamp today, 20:12:

the "year (and year)" format works if time string has been found -- otherwise format recognised hh mm.

i don't know mean when saying a time string has been found. can see behaviour using following line:

var_dump(date("y-m-d h:i:s", strtotime('2012'))); // output: string(19) "2013-07-22 20:12:00" 

this leads result 2013.