PHPで現在の週番号と月の第何週かを取得する方法を徹底解説

$weekNumber = date("W");
echo "現在の週番号は: " . $weekNumber;

function getWeekOfMonth($date) {
    // 指定した日付の週番号を取得
    $firstDayOfMonth = date("Y-m-01", strtotime($date));
    $weekOfMonth = ceil((date("j", strtotime($date)) + date("N", strtotime($firstDayOfMonth)) - 1) / 7);
    return $weekOfMonth;
}

$date = "2024-10-24";
echo $date . "は月の第" . getWeekOfMonth($date) . "週目です。";

$isoWeekNumber = date("W");
$isoYear = date("o");
echo "現在のISO-8601準拠の週番号は: " . $isoWeekNumber . "（年: " . $isoYear . "）";

use Carbon\Carbon;

// 現在の日付を取得
$currentDate = Carbon::now();

// ISO-8601準拠の週番号を取得
$weekNumber = $currentDate->weekOfYear;
echo "現在のISO-8601準拠の週番号は: " . $weekNumber;

// 任意の日付の週番号を取得
$date = Carbon::createFromDate(2024, 10, 24);
$weekNumber = $date->weekOfYear;
echo "2024年10月24日はISO-8601準拠で第" . $weekNumber . "週目です。";

$date = "2024-05-15";
$weekNumber = date("W", strtotime($date));
echo $date . "は年の第" . $weekNumber . "週目です。";

$futureDate = date("Y-m-d", strtotime("+1 year"));
$weekNumber = date("W", strtotime($futureDate));
echo $futureDate . "は年の第" . $weekNumber . "週目です。";

use Carbon\Carbon;

// 過去の日付
$pastDate = Carbon::createFromDate(2023, 3, 15);
$pastWeekNumber = $pastDate->weekOfYear;
echo "2023年3月15日はISO-8601準拠で第" . $pastWeekNumber . "週目です。";

// 未来の日付
$futureDate = Carbon::now()->addMonths(6);
$futureWeekNumber = $futureDate->weekOfYear;
echo "6か月後の週番号は: " . $futureWeekNumber;

$salesData = [
    "2024-01-03" => 100,
    "2024-01-10" => 150,
    "2024-01-17" => 200,
    "2024-02-01" => 250,
];

$weeklySales = [];
foreach ($salesData as $date => $sales) {
    $week = date("W", strtotime($date));
    if (!isset($weeklySales[$week])) {
        $weeklySales[$week] = 0;
    }
    $weeklySales[$week] += $sales;
}

foreach ($weeklySales as $week => $totalSales) {
    echo "第" . $week . "週の売上: " . $totalSales . "円\n";
}

function getWeekOfMonth($date) {
    $firstDayOfMonth = date("Y-m-01", strtotime($date));
    $dayOfMonth = date("j", strtotime($date));
    $firstDayOfWeek = date("N", strtotime($firstDayOfMonth)); // 月の最初の日の曜日（1: 月曜日, 7: 日曜日）
    $weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek - 1) / 7);
    return $weekOfMonth;
}

$date = "2024-10-24";
echo $date . "は月の第" . getWeekOfMonth($date) . "週目です。";

function getWeekOfMonthSundayStart($date) {
    $firstDayOfMonth = date("Y-m-01", strtotime($date));
    $dayOfMonth = date("j", strtotime($date));
    $firstDayOfWeek = date("w", strtotime($firstDayOfMonth)); // 日曜日を0とする
    $weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek) / 7);
    return $weekOfMonth;
}

$date = "2024-10-24";
echo $date . "は（日曜始まりで）月の第" . getWeekOfMonthSundayStart($date) . "週目です。";

function isEventWeek($date, $targetWeek) {
    $weekOfMonth = getWeekOfMonth($date);
    return $weekOfMonth == $targetWeek;
}

$eventDate = "2024-11-13"; // 例: 2024年11月13日（水曜日）
$targetWeek = 2; // 第2週

if (isEventWeek($eventDate, $targetWeek)) {
    echo $eventDate . "は第" . $targetWeek . "週のイベント週です。";
} else {
    echo $eventDate . "はイベント週ではありません。";
}

$events = [
    ["date" => "2024-10-24", "title" => "プロジェクト会議"],
    ["date" => "2024-10-30", "title" => "月次レビュー"],
    ["date" => "2024-11-05", "title" => "チームビルディング"],
];

$currentWeek = date("W");
$filteredEvents = array_filter($events, function($event) use ($currentWeek) {
    return date("W", strtotime($event["date"])) == $currentWeek;
});

echo "今週のイベント一覧:\n";
foreach ($filteredEvents as $event) {
    echo $event["date"] . ": " . $event["title"] . "\n";
}

function scheduleMonthlyEvent($year, $month, $targetWeek, $weekday) {
    // 月の1日から開始してターゲットの週と曜日に一致する日付を見つける
    $date = new DateTime("$year-$month-01");
    $firstWeekday = $date->format("N"); // 曜日（1: 月曜日, 7: 日曜日）
    $daysToAdd = ($weekday - $firstWeekday + 7) % 7 + ($targetWeek - 1) * 7;
    $date->modify("+$daysToAdd days");
    return $date->format("Y-m-d");
}

$eventDate = scheduleMonthlyEvent(2024, 11, 1, 5); // 第1週の金曜日（5）
echo "定例会議は " . $eventDate . " に開催されます。";

$activityLogs = [
    ["date" => "2024-10-01", "action" => "login"],
    ["date" => "2024-10-04", "action" => "purchase"],
    ["date" => "2024-10-10", "action" => "login"],
    ["date" => "2024-10-14", "action" => "purchase"],
];

$weeklyActivity = [];
foreach ($activityLogs as $log) {
    $weekNumber = date("W", strtotime($log["date"]));
    if (!isset($weeklyActivity[$weekNumber])) {
        $weeklyActivity[$weekNumber] = 0;
    }
    $weeklyActivity[$weekNumber]++;
}

foreach ($weeklyActivity as $week => $count) {
    echo "第" . $week . "週のアクティビティ数: " . $count . "\n";
}

// 日曜日を週の開始日とした計算例
$firstDayOfMonth = date("Y-m-01", strtotime($date));
$dayOfMonth = date("j", strtotime($date));
$firstDayOfWeek = date("w", strtotime($firstDayOfMonth)); // 日曜日を0とする
$weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek) / 7);

$date = "2024-12-31";
$weekNumber = date("W", strtotime($date));
$year = date("o", strtotime($date));
echo $date . "はISO-8601規格での週番号: 第" . $weekNumber . "週（年: " . $year . "）です。";

function getAccurateWeekOfMonth($date) {
    $firstDayOfMonth = date("Y-m-01", strtotime($date));
    $dayOfMonth = date("j", strtotime($date));
    $firstDayOfWeek = date("N", strtotime($firstDayOfMonth));
    $weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek - 1) / 7);

    // 月末の日付調整
    $lastDayOfMonth = date("Y-m-t", strtotime($date));
    if (date("j", strtotime($lastDayOfMonth)) - $dayOfMonth < 7 && date("N", strtotime($lastDayOfMonth)) < $firstDayOfWeek) {
        $weekOfMonth--;
    }

    return $weekOfMonth;
}

date_default_timezone_set("Asia/Tokyo");
$weekNumber = date("W");

$weekNumber = date("W");

if ($weekNumber == 42) {
    echo "第42週の特別キャンペーンを実施中です！";
} else {
    echo "通常の週です。";
}

function getWeekOfMonth($date) {
    $firstDayOfMonth = date("Y-m-01", strtotime($date));
    $dayOfMonth = date("j", strtotime($date));
    $firstDayOfWeek = date("N", strtotime($firstDayOfMonth));
    $weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek - 1) / 7);
    return $weekOfMonth;
}

$currentWeekOfMonth = getWeekOfMonth(date("Y-m-d"));

if ($currentWeekOfMonth == 2) {
    echo "今週は月の第2週です。定例ミーティングを行います。";
} else {
    echo "今週は通常の週です。";
}

if ($currentWeekOfMonth == 1 || $currentWeekOfMonth == 3) {
    echo "今週は特別イベントを開催します！";
} else {
    echo "通常スケジュールです。";
}

$dayOfWeek = date("N"); // 月曜日は1、日曜日は7

if ($currentWeekOfMonth == 1 && $dayOfWeek == 1) {
    echo "今週は第1週の月曜日です。月初ミーティングを行います。";
} else {
    echo "通常業務を行っています。";
}

$events = [];

function addEvent($weekNumber, $eventDescription) {
    global $events;
    $events[$weekNumber] = $eventDescription;
}

$weekNumber = date("W");

// 第10週と第25週にイベントを追加
addEvent(10, "春のキャンペーン開始");
addEvent(25, "夏の特別セール開始");

if (isset($events[$weekNumber])) {
    echo "今週のイベント: " . $events[$weekNumber];
} else {
    echo "今週は特別なイベントはありません。";
}

$dayOfWeek = date("N");

if ($dayOfWeek == 5) {
    echo "今週の締め切りタスクを確認しましょう！";
} elseif ($dayOfWeek == 7) {
    echo "週末のリマインダー：休息を取りましょう。";
} else {
    echo "通常のタスクを進めてください。";
}

composer require --dev phpunit/phpunit

use PHPUnit\Framework\TestCase;

class WeekNumberTest extends TestCase
{
    // 週番号を取得する関数
    private function getWeekNumber($date)
    {
        return date("W", strtotime($date));
    }

    // テストケース1: 年初の週番号をテスト
    public function testGetWeekNumberForJanuary()
    {
        $date = "2024-01-01";
        $expectedWeekNumber = "01";
        $this->assertEquals($expectedWeekNumber, $this->getWeekNumber($date), "1月1日の週番号は01であるべきです");
    }

    // テストケース2: 年末の週番号をテスト
    public function testGetWeekNumberForDecember()
    {
        $date = "2024-12-31";
        $expectedWeekNumber = "01"; // 12月31日は次年の第1週として扱われる場合がある
        $this->assertEquals($expectedWeekNumber, $this->getWeekNumber($date), "12月31日の週番号は01であるべきです");
    }

    // テストケース3: 中間日付の週番号をテスト
    public function testGetWeekNumberForOctober()
    {
        $date = "2024-10-24";
        $expectedWeekNumber = "43";
        $this->assertEquals($expectedWeekNumber, $this->getWeekNumber($date), "10月24日の週番号は43であるべきです");
    }
}

class WeekOfMonthTest extends TestCase
{
    // 月の第何週かを判定する関数
    private function getWeekOfMonth($date)
    {
        $firstDayOfMonth = date("Y-m-01", strtotime($date));
        $dayOfMonth = date("j", strtotime($date));
        $firstDayOfWeek = date("N", strtotime($firstDayOfMonth));
        $weekOfMonth = ceil(($dayOfMonth + $firstDayOfWeek - 1) / 7);
        return $weekOfMonth;
    }

    // テストケース1: 月初の週判定
    public function testGetWeekOfMonthForFirstWeek()
    {
        $date = "2024-10-01";
        $expectedWeekOfMonth = 1;
        $this->assertEquals($expectedWeekOfMonth, $this->getWeekOfMonth($date), "10月1日は第1週であるべきです");
    }

    // テストケース2: 月中の週判定
    public function testGetWeekOfMonthForMiddleOfMonth()
    {
        $date = "2024-10-15";
        $expectedWeekOfMonth = 3;
        $this->assertEquals($expectedWeekOfMonth, $this->getWeekOfMonth($date), "10月15日は第3週であるべきです");
    }

    // テストケース3: 月末の週判定
    public function testGetWeekOfMonthForEndOfMonth()
    {
        $date = "2024-10-31";
        $expectedWeekOfMonth = 5;
        $this->assertEquals($expectedWeekOfMonth, $this->getWeekOfMonth($date), "10月31日は第5週であるべきです");
    }
}

public function testLeapYearWeek()
{
    $date = "2024-02-29";
    $expectedWeekNumber = "09";
    $this->assertEquals($expectedWeekNumber, $this->getWeekNumber($date), "2024年2月29日は第9週であるべきです");
}