# How to add or subtract dates in PHP

* For current *date*

````php
// You can add or subtract days, weeks, months, years using
// (+/-)(number) (day|week|month|year)
// e.g. "+1 year"

$currentDate = date('Y-m-d');
// Print: 2018-09-06
$currentDateMinusOneMonth = date('Y-m-d', strtotime('-1 month', strtotime($currentDate)));
// Print: 2018-08-06
````

* For specific *dates*

````php
$specificDate = strtotime('2000-01-01');
$specificDateMinusOneWeek = date('Y-m-d', strtotime("-1 week", $specificDate));
// Print: 1999-12-25
````

* Tips

  * How to get the last day of the current month

    ````php
    $lastDayOfCurrentMonth = date('Y-m-t');
    ````

  * How to get the last day of the previous month (and *n* months)

    ````php
    $lastDayOfPreviousMonth = date('Y-m-t', strtotime('-1 month',strtotime(date('Y-m'))));
    $lastDayOfNPreviousMonth = date('Y-m-t', strtotime('-n month',strtotime(date('Y-m'))));
    // n: any number
    ````