PHP Date and Time Reference

How it works

DateTimeImmutable, DateInterval and DateTimeZone give explicit objects for many application tasks. Procedural helpers remain useful, but functions that depend on defaults can hide environment-sensitive behaviour. Fixed elapsed seconds and calendar arithmetic differ across timezone transitions. Parsing must check errors and warnings, not merely whether an object was returned. Locale-oriented deprecated formatting APIs should not become the default design for new code.

Run it locally

Run this complete source locally with PHP 8.2 or newer. Save it using the filename shown and run the command below. PHP is not currently available in Bhylu’s browser playground. Apache and MySQL are not needed for an ordinary CLI example.

php -l ref-time.php
php ref-time.php

Download this source as a local PHP lab file. Keep lab files separate from the Bhylu project and production data.

Example

<?php
declare(strict_types=1);

$date = new DateTimeImmutable("2026-02-01",new DateTimeZone("UTC"));
echo $date->format("Y-m-t"), "\n";
echo in_array("Asia/Kolkata",DateTimeZone::listIdentifiers(),true) ? "Timezone available\n" : "Missing timezone\n";

Expected result

2026-02-28
Timezone available

The month-end format uses an explicit date and timezone, so it does not depend on today’s date. The identifier list confirms a supported named timezone rather than inferring rules from an abbreviation. A displayed date is still only one representation of the underlying date/time contract.

Contracts to check

Related API names

This alphabetic inventory helps locate related calls. Availability was checked in the review runtime; it is not a recommendation to use every API or a claim that every overload/function was executed. Read the official entry for version, extension, failure and security details.