Oihana PHP

diffInDays.php

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Functions

diffInDays()  : int
Returns the signed number of calendar days between two instants.

Functions

diffInDays()

Returns the signed number of calendar days between two instants.

diffInDays(DateTimeInterface $a, DateTimeInterface $b) : int

DateTimeInterface::diff() is a trap for this : its DateInterval::$d is only the day-of-month component of a y/m/d/h/i/s breakdown, which resets every month — over a 34-day gap it reads 3, not 34. This function reads the interval's $days instead (the true total, calendar-aware — a day that has 23 or 25 hours across a DST transition still counts as one day) and applies $invert as the sign, so the result is positive when $b is later than $a, negative when it is earlier.

Parameters
$a : DateTimeInterface

The starting instant.

$b : DateTimeInterface

The ending instant.

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

diffInDays( new DateTimeImmutable( '2026-01-01' ) , new DateTimeImmutable( '2026-02-04' ) ) ; // 34
diffInDays( new DateTimeImmutable( '2026-02-04' ) , new DateTimeImmutable( '2026-01-01' ) ) ; // -34
diffInDays( new DateTimeImmutable( '2026-01-01' ) , new DateTimeImmutable( '2026-01-01' ) ) ; // 0
author

Marc Alcaraz (ekameleon)

since
1.2.0
Return values
int —

The number of calendar days from $a to $b ; negative if $b is before $a.

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