DateInterval and DatePeriod
Learn date differences with DateInterval and walking date ranges with DatePeriod.
Durations with DateInterval
The DateInterval class represents a duration: one day, one month, one hour and so on. The duration is given as an ISO 8601 string: 'P1D' is one day, 'P1M' one month, 'P1Y' one year, 'PT1H' one hour.
You add one day to a DateTime object with ->add(new DateInterval('P1D')). Use ->sub() to subtract.
P starts the period, T starts the time part; dates come after P, times after T.
Date ranges with DatePeriod
The DatePeriod class walks a date range at a fixed interval. It takes a start DateTime, a DateInterval and an end DateTime.
For example, to list every day from 1 January to 7 January, build new DatePeriod($start, new DateInterval('P1D'), $end) and loop with foreach. Each iteration yields a DateTime object.
This is very handy for range-based work like calendars or reports.
Exercise Add one day to a DateTime
Create an object with new DateTime('2024-01-01') and assign it to $date. Then add one day with $date->add(new DateInterval('P1D')) and print it with echo $date->format('Y-m-d').
Show example solution
Create with $date = new DateTime('2024-01-01'); add $date->add(new DateInterval('P1D')); then write echo $date->format('Y-m-d');
Example solution:
<?php
date_default_timezone_set('UTC');
$date = new DateTime('2024-01-01');
$date->add(new DateInterval('P1D'));
echo $date->format('Y-m-d');Test yourself
-
What does new DateInterval('P1D') represent?
- A 1-hour duration
- A 1-day duration
- A 1-month duration
- A 1-year duration
Show answer
A 1-day duration — Correct. 'P1D' represents a one-day duration.
-
Create a one-day interval
$interval = new DateInterval('____');Show answer
$interval = new DateInterval('P1D'); -
Match duration specs
- 'P1D'
- 1 day
- 'P1M'
- 1 month
- 'P1Y'
- 1 year
- 'PT1H'
- 1 hour