Oihana PHP

isSameDay.php

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Functions

isSameDay()  : bool
Tells whether two instants fall on the same calendar day.

Functions

isSameDay()

Tells whether two instants fall on the same calendar day.

isSameDay(DateTimeInterface $a, DateTimeInterface $b[, DateTimeZone|null $timezone = null ]) : bool

The same physical instant can be a different calendar date depending on the timezone it is read in — 2026-01-01 00:30:00 UTC is still 2025-12-31 in America/Los_Angeles. Both dates are converted to $timezone before their calendar date is compared ; it defaults to the timezone carried by $a, so the common, no-argument call answers "is $b the same day as $a, as seen from $a's own timezone". Pass $timezone explicitly to compare from a third, unrelated timezone instead.

Parameters
$a : DateTimeInterface

The first instant.

$b : DateTimeInterface

The second instant.

$timezone : DateTimeZone|null = null

The timezone the comparison is made in. Defaults to $a's own timezone.

Tags
example 
use function oihana\core\date\isSameDay;

$a = new DateTimeImmutable( '2026-01-01 01:00:00' , new DateTimeZone( 'UTC' ) );
$b = new DateTimeImmutable( '2026-01-01 20:00:00' , new DateTimeZone( 'UTC' ) );

isSameDay( $a , $b ) ; // true — both January 1st in UTC, $a's own timezone (the default)

// Compared from Tokyo (UTC+9) instead, $a is still Jan 1st (10:00) but $b has
// already rolled over to Jan 2nd (05:00) : same two instants, different verdict.
isSameDay( $a , $b , new DateTimeZone( 'Asia/Tokyo' ) ) ; // false
author

Marc Alcaraz (ekameleon)

since
1.2.0
Return values
bool —

true if $a and $b fall on the same calendar day in $timezone, false otherwise.

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