add()
add(string $amount) : $this
Adds an amount of days, months, years, hours, minutes and seconds to a DateTimeObject.
Parameters
string | $amount | You can specify the amount in ISO8601 format (example: 'P14D' = 14 days; 'P1DT12H' = 1 day 12 hours), or as a date string (example: '1 day', '2 months', '3 year', '2 days + 10 minutes'). |