PHP jddayofweek() 函数

jddayofweek(int $julian_day, int $mode = CAL_DOW_DAYNO): mixed

// 获取2000年1月1日的星期几（默认模式）
$jd = gregoriantojd(1, 1, 2000);
$day_of_week = jddayofweek($jd);
echo "2000年1月1日是星期: " . $day_of_week;

2000年1月1日是星期: 6

// 使用不同模式获取星期信息
$jd = gregoriantojd(1, 1, 2000);

$number = jddayofweek($jd, CAL_DOW_DAYNO);
$short = jddayofweek($jd, CAL_DOW_SHORT);
$long = jddayofweek($jd, CAL_DOW_LONG);

echo "数字模式: {$number}\n";
echo "缩写模式: {$short}\n";
echo "全称模式: {$long}";

数字模式: 6
缩写模式: Sat
全称模式: Saturday

// 获取重要历史事件发生在星期几
$historical_dates = [
    "美国独立宣言" => [7, 4, 1776],
    "人类首次登月" => [7, 20, 1969],
    "柏林墙倒塌" => [11, 9, 1989],
    "互联网诞生" => [1, 1, 1983],
    "911事件" => [9, 11, 2001]
];

foreach ($historical_dates as $event => $date) {
    list($month, $day, $year) = $date;
    $jd = gregoriantojd($month, $day, $year);
    $weekday = jddayofweek($jd, CAL_DOW_LONG);
    echo "{$event} ({$year}-{$month}-{$day}): {$weekday}\n";
}

美国独立宣言 (1776-7-4): Thursday
人类首次登月 (1969-7-20): Sunday
柏林墙倒塌 (1989-11-9): Thursday
互联网诞生 (1983-1-1): Saturday
911事件 (2001-9-11): Tuesday

// 计算未来某个日期的星期几
$target_date = "2030-01-01";
list($year, $month, $day) = explode('-', $target_date);
$jd = gregoriantojd($month, $day, $year);
$weekday = jddayofweek($jd, CAL_DOW_LONG);

echo "{$target_date} 是: {$weekday}";

2030-01-01 是: Tuesday

// 创建通用的星期几获取函数
function get_weekday_info($month, $day, $year) {
    $jd = gregoriantojd($month, $day, $year);

    return [
        'number' => jddayofweek($jd, CAL_DOW_DAYNO),
        'short' => jddayofweek($jd, CAL_DOW_SHORT),
        'long' => jddayofweek($jd, CAL_DOW_LONG),
        'chinese' => ['日', '一', '二', '三', '四', '五', '六'][jddayofweek($jd, CAL_DOW_DAYNO)]
    ];
}

// 使用函数获取信息
$info = get_weekday_info(12, 25, 2023);
echo "2023年圣诞节:\n";
echo "数字: {$info['number']}\n";
echo "英文缩写: {$info['short']}\n";
echo "英文全称: {$info['long']}\n";
echo "中文: 星期{$info['chinese']}";

2023年圣诞节:
数字: 1
英文缩写: Mon
英文全称: Monday
中文: 星期一

// 验证jddayofweek与date函数的一致性
$test_dates = [
    [1, 1, 2000],
    [7, 4, 1776],
    [12, 25, 2023],
    [2, 29, 2020]
];

foreach ($test_dates as $date) {
    list($month, $day, $year) = $date;
    $jd = gregoriantojd($month, $day, $year);

    // 使用jddayofweek
    $jd_weekday = jddayofweek($jd, CAL_DOW_LONG);

    // 使用date函数验证
    $timestamp = mktime(0, 0, 0, $month, $day, $year);
    $date_weekday = date('l', $timestamp);

    echo "日期: {$year}-{$month}-{$day}\n";
    echo "jddayofweek: {$jd_weekday}\n";
    echo "date函数: {$date_weekday}\n";
    echo "结果: " . ($jd_weekday === $date_weekday ? "一致" : "不一致") . "\n\n";
}

日期: 2000-1-1
jddayofweek: Saturday
date函数: Saturday
结果: 一致

日期: 1776-7-4
jddayofweek: Thursday
date函数: Thursday
结果: 一致

日期: 2023-12-25
jddayofweek: Monday
date函数: Monday
结果: 一致

日期: 2020-2-29
jddayofweek: Saturday
date函数: Saturday
结果: 一致