businessDays.php

<?php

use Org_Heigl\Holidaychecker\Holidaychecker;
use Org_Heigl\Holidaychecker\HolidayIteratorFactory;

$factory  = new HolidayIteratorFactory();
$iterator = $factory->createIteratorFromISO3166('DE');
$checker  = new Holidaychecker($iterator);

$startDate = new DateTimeImmutable('2022-10-10');
$endDate   = new DateTimeImmutable('2022-10-31');
$dateIterator = new DatePeriod(
    $startDate,
    new DateInterval('P1D'),
    $endDate
);

$numberOfBusinessDays = 0;

foreach ($dateIterator as $date) {
    if ($checker->check($date)->isHoliday()) {
        continue;
    }

    // Your business-Logic here
    $numberOfBusinessDays++;
}

echo sprintf(
    'There are %1$d business-days between %2$s and %3$s',
    $numberOfBusinessDays,
    $startDate->format('d.m.Y'),
    $endDate->format('d.m.Y'),
);