根据区域设置查找第一周和最后一周

Question

我正在尝试根据区域设置查找第一周和最后一周。

在美国，一周通常从星期日开始，但在其他国家/地区可能会在另一天开始 - 例如周一甚至周六。

setlocale(LC_ALL, "en_US.UTF-8");
date_default_timezone_set("America/New_York");

$start_week = (new DateTimeImmutable());
$start_week = $start_week->modify('this week');
$end_week = $start_week->modify('this week +6 days');

$interval = new DateInterval('P1D');
$week_range = new DatePeriod($start_week, $interval, $end_week);

foreach($week_range as $week_day) {
  // $week_day starts with Monday, supposed to be Sunday
}

Answer 1

一种方法是使用IntlCalendar 类。它有一个方法getFirstDayofWeek()，返回一个整数，对应IntlCalendar中的DOW_常量：

常量整数 DOW_SUNDAY = 1 ;
常量整数 DOW_MONDAY = 2 ;
常量整数 DOW_TUESDAY = 3 ;
常量整数 DOW_WEDNESDAY = 4 ;
常量整数 DOW_THURSDAY = 5 ;
常量整数 DOW_FRIDAY = 6 ;
常量整数 DOW_SATURDAY = 7 ;

在为开始日调用DateTimeImmutable::modify() 时，使用它来为开始日添加天数。在this phpfiddle 中使用三个语言环境（即en_US、es_ES、sw_KE）查看它。

$locale = 'es_ES'; //Spain Spanish locale
$cal1 = IntlCalendar::createInstance(NULL, $locale);
$firstDayOfWeek = $cal1->getFirstDayOfWeek();
$daysToAdd = $firstDayOfWeek - 2; //difference from US M-Sunday 
echo 'locale: '.$local.' first day of week: '.$cal1->getFirstDayOfWeek().' days to add: '.$daysToAdd.'<br />';
$start_week = new DateTimeImmutable();
$start_week = $start_week->modify('this week +'.$daysToAdd.' days');
$end_week = $start_week->modify('+6 days');
$interval = new DateInterval('P1D');
$week_range = new DatePeriod($start_week, $interval, $end_week);

foreach($week_range as $week_day) {
    echo 'week day: '.$week_day->format('l m/d/Y').'<br />';
}