How do I minus one month from Year-Month 2019-03

Question

I am trying to subtract one month from the current receiving year-month (2019-03)

echo $payroll['month'];
echo $newdate = date("Y-m", strtotime("-1 months",$payroll['month']));

but it through error as

2019-03

A PHP Error was encountered
Severity: Notice

Message: A non well formed numeric value encountered

what I want 2019-03 to subtract one month so I will get 2019-02

Possible duplicate of [Stackoverflow](https://stackoverflow.com/questions/38738910/php-subtract-1-month-from-date-formated-with-date-m-y) — Shubham Baranwal, Mar 05 '19 at 04:24

score 3 · Answer 1 · edited Mar 05 '19 at 04:43

3

You can try the following solution:

date('Y-m', strtotime($payroll['month'] . ' - 1 month'))

edited Mar 05 '19 at 04:43

Ankur Tiwari

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answered Mar 05 '19 at 04:20

luffy1727

39
2

score 2 · Accepted Answer · answered Mar 05 '19 at 04:21

2

Try this -

echo $newdate = date('Y-m', strtotime('-1 months', strtotime($payroll['month'])));

answered Mar 05 '19 at 04:21

Shubham Baranwal

2,492
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Pupil · Answer 3 · 2019-03-05T12:06:41.180

So many nice answers here.

Just note that this can be done with PHP's DateTime class.

$date = new DateTime("2019-03-03");
$date->sub(new DateInterval('P1M')); // P -> Period 1 Month
echo $date->format("Y-m")
// Outputs: 2019-02

A quick note from strtotime() 's official documentation.

Note: Using this function for mathematical operations is not advisable. It is better to use DateTime::add() and DateTime::sub() in PHP 5.3 and later, or DateTime::modify() in PHP 5.2.

Ankur Tiwari · Answer 4 · 2019-03-05T04:28:14.457

0

You can add one more strtotime to get your desired output

$payroll['month'] = "2019-03";
echo $payroll['month'];
echo $newdate = date("Y-m", strtotime("-1 months", strtotime($payroll['month'])));

Another way to do the same is:

date('Y-m', strtotime($payroll['month'] . '-1 months'))

This will also work for you.

edited Mar 05 '19 at 04:28

answered Mar 05 '19 at 04:23

Ankur Tiwari

2,762
2
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score 0 · Answer 5 · answered Mar 05 '19 at 12:20

Beware... simply adding or substracting one month on a yyyy-mm string may render unexpected results under some edge cases. It happens that I use that format on a site I built (for payrolls and other stuff) and when the calculation was done on February 28 (IIRC) and other edge cases, the result wasn't always what I needed it to be (i.e., the next or previous month)

It's a little bit more code, but my advice would be:

$first_of_month = date('Y-m-01', strtotime($payroll['month']));
$newdate = date('Y-m', strtotime($first_of_month."-1 month"));

By forcing your initial value to be a full Y-m-d date on the first day of the month (the day being irrelevant for you, as it's used only for the calculation) you can make sure that the calculation will be correct every time

How do I minus one month from Year-Month 2019-03

5 Answers5