(PHP 5 >= 5.5.0, PHP 7, PHP 8, PECL >= 3.0.0a1)
IntlCalendar::setFirstDayOfWeek — Set the day on which the week is deemed to start
Object-oriented style
public IntlCalendar::setFirstDayOfWeek(int $dayOfWeek): true
Procedural style
intlcal_set_first_day_of_week(IntlCalendar $calendar, int $dayOfWeek): true
Defines the day of week deemed to start the week. This affects the behavior of fields that depend on the concept of week start and end such as IntlCalendar::FIELD_WEEK_OF_YEAR and IntlCalendar::FIELD_YEAR_WOY.
calendarAn IntlCalendar instance.
dayOfWeek One of the constants IntlCalendar::DOW_SUNDAY, IntlCalendar::DOW_MONDAY, …, IntlCalendar::DOW_SATURDAY.
Always returns true.
Example #1 IntlCalendar::setFirstDayOfWeek()
<?php
ini_set('date.timezone', 'Europe/Lisbon');
ini_set('intl.default_locale', 'es_ES');
$cal = IntlCalendar::createInstance();
$cal->set(2013, 5 /* June */, 30); // A Sunday
var_dump($cal->getFirstDayOfWeek()); // 2 (Monday)
echo IntlDateFormatter::formatObject($cal, <<<EOD
'local day of week: 'cc'
week of month : 'W'
week of year : 'ww
EOD
), "\n";
$cal->setFirstDayOfWeek(IntlCalendar::DOW_SUNDAY);
echo IntlDateFormatter::formatObject($cal, <<<EOD
'local day of week: 'cc'
week of month : 'W'
week of year : 'ww
EOD
), "\n"; The above example will output:
int(2) local day of week: 7 week of month : 4 week of year : 26 local day of week: 1 week of month : 5 week of year : 27
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https://www.php.net/manual/en/intlcalendar.setfirstdayofweek.php