Date Arithmetic in PHP

Question

Is there a PHP function I can use to do something like the following:

Get the date 6 months ago (e.g. now - 6 months)?
Get the date 2 years from now (e.g. now + 2 years)?

I thought PHP's `strtotime()` was fairly ubiquitous. – Russell Dias Nov 23 '11 at 00:38 — Russell Dias, Nov 23 '11 at 00:38

score 33 · Accepted Answer · edited Sep 23 '17 at 20:45

33

Yes, there is: strtotime():

6 months ago: strtotime("-6 months");
2 years: strtotime("+2 years");

These will return Unix timestamps. So you might want to put the result into date() or localtime() or gmtime().

Please do not try to subtract 6 months or add 2 years of seconds to time(). This does not take into account things like daylight saving or leap seconds and still gives you a value in seconds which is unlikely to be the precision you need. Let the library functions do it.

edited Sep 23 '17 at 20:45

Mofi

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answered Nov 23 '11 at 00:38

staticsan

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Thanks. `strtotime` is exactly what I needed. – StackOverflowNewbie Nov 23 '11 at 00:43
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The date arithmetic is a bit questionable. For example `date('Y-m-d', strtotime('-1 month', strtotime('2013-03-31')))` gives `2013-03-03`. – Tamlyn Apr 30 '13 at 11:21
@Tammlyn That is an interesting bug! I'm fairly sure that strtotime calls the underlying glibc call. – staticsan May 03 '13 at 07:02
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Oh - I know why it did that: It made Mar 31 to Feb 31 which doesn't exist, so then it converted that to Mar 3. That's a tricky error to solve! – staticsan Apr 07 '14 at 03:01

score 12 · Answer 2 · answered Nov 23 '11 at 00:38

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Like this:

$date6monthsago = strtotime('-6 months');
$date2year = strtotime('+2 year');

answered Nov 23 '11 at 00:38

Book Of Zeus

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score 6 · Answer 3 · answered Nov 23 '11 at 07:03

Choose according to your use following code..

echo date('m/d/Y',strtotime("-6 months")); //ago 6month o/p 05/23/2011 
echo date('d-m-Y',strtotime("6 months"));  //comming 6month o/p 23-05-2012
echo date('m.d.Y',strtotime("+2 years"));  //comming year o/p 11.23.2013

score 0 · Answer 4 · answered Jul 25 '13 at 11:27

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http://de2.php.net/manual/en/datetime.add.php and similar "new" methods may also be your friend.

answered Jul 25 '13 at 11:27

patriziotomato

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Date Arithmetic in PHP

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