FIX: Custom date format with date_add and date_sub

To use this plugin with custom date format on date_add and date_sub here is how to easily fix it.
Go to the Plugins -> Plugin Editor then select Date Calculator. You are now on editable date-calculator.php

FOR date_add
There you need to find line 203 and replace with this code:
$datecalc = date($format, mktime(0, 0, 0, date(“m”)+$month, date(“d”)+$day, date(“Y”)+$year));

FOR date_sub
Find line 244 and replace with this code:
$datecalc = date($format, mktime(0, 0, 0, date(“m”)-$month, date(“d”)-$day, date(“Y”)-$year));

Now you can use custom date format.