Get previous month value in PHP

Question

I have used the below PHP function to get the previous month,

$currmonth = date(\'m\', strtotime(\'-1 month\'));

It was working fine and I

Answer 1

strtotime() works accurately. The problem is what you ask it to return.

"-1 month" is not the same as "previous month". It is the same as "subtract 1 from current month then normalize the result".

On 2017-05-31, subtracting 1 from current month gets 2017-04-31 which is not a valid date. After normalization, it becomes 2017-05-01, hence the result you get.

There are more than one way to get the value you need. For example:

// Today
$now = new DateTime('now');
// Create a date interval string to go back to the first day of the previous month
$int = sprintf('P1M%dD', $now->format('j')-1);
// Get the first day of the previous month as DateTime
$fdopm = $now->sub(new DateInterval($int));
// Verify it works
echo($fdopm->format('Y-m-d'));

// On 2017-05-31 it should print:
// 2017-04-01