-1 Month does not return to the previous month - PHP

Question

Wore the strtotime() to return to the previous month and always take the last day of the previous month, did so:

$data_teste = date('Y-m-t', strtotime('-1 month'));

And it was working so far (31-10-2018), instead of going back to 30-09-2018 it showed the day 31-10-2018, apparently the function goes back 30 days and not to "the previous month" as I thought it did. Does anyone know a way out of this situation?

Answer 1

When you use relative formats, you must "relativize" the result.

Being today 31/10/2018, using -1 month or last month, the date will be 31/09/2018.

When this date is converted to team, or any other date function, it is interpreted as 01/10/2018.

In your code it is easy to interpret that you always want the last day of the month, in this case, use a more direct approach:

$date_teste = date('Y-m-d', strtotime('last day of last month'));

Or

$date_teste = new DateTime('last day of last month');

See the examples: https://3v4l.org/SUHoX