PHP календарь на месяц

Функция для вывода календаря на заданный месяц.

function getCalendarForMonth($month, $year)
{
    $arMonthDay = array();
    $currentDayUnixTime = strtotime(date("{$year}-{$month}-01"));
    $currentMonth = date('m', $currentDayUnixTime);
    $dayWeekIndex = 1;
    $weekIndex = 1;
    while($month == $currentMonth) {
        $currentDayWeekNumber = date("N", $currentDayUnixTime);
        if($currentDayWeekNumber == $dayWeekIndex) {
            $arMonthDay[$weekIndex][$dayWeekIndex] = date('d', $currentDayUnixTime);
            $currentDayUnixTime = strtotime("+1 day", $currentDayUnixTime);
            $currentMonth = date('m', $currentDayUnixTime);
        }
        else {
            $arMonthDay[$weekIndex][$dayWeekIndex] = "";
        }

        if($dayWeekIndex == 7) {
            $weekIndex++;
            $dayWeekIndex = 1;
        }
        else {
            $dayWeekIndex++;
        }
    }
    if(!empty($arMonthDay[$weekIndex])) {
        $arMonthDay[$weekIndex] = array_pad($arMonthDay[$weekIndex], 7, "");
    }
    return $arMonthDay;
}

Пример

Теперь используя эту функцию можно вывести календарь, например на ноябрь 2017 года

<?php $arMonthDay = getCalendarForMonth(11, 2017); ?>
<table class="table">
    <thead>
        <th>Пн</th>
        <th>Вт</th>
        <th>Ср</th>
        <th>Чт</th>
        <th>Пт</th>
        <th>Сб</th>
        <th>Вс</th>
    </thead>
    <tbody>
        <?php foreach($arMonthDay as $arWeek) { ?>
        <tr>
            <?php foreach($arWeek as $day) { ?>
            <td><?php echo $day;?></td>
            <?php } ?>
        </tr>
        <?php } ?>
    </tbody>
</table>

В результате получится примерно следующая таблица:

Доработки

В зависимости от задачи функцию можно доработать, например добавить отметку о том что день является текущим (сегодняшним).

function getCalendarForMonth($month, $year)
{
    $arMonthDay = array();
    $currentDayUnixTime = strtotime(date("{$year}-{$month}-01"));
    $currentMonth = date('m', $currentDayUnixTime);
    $dayWeekIndex = 1;
    $weekIndex = 1;
    while($month == $currentMonth) {
        $currentDayWeekNumber = date("N", $currentDayUnixTime);
        if($currentDayWeekNumber == $dayWeekIndex) {
            $arMonthDay[$weekIndex][$dayWeekIndex] = array(
                "day" => date('d', $currentDayUnixTime),
                "today" => (date("Y-m-d") == date("Y-m-d", $currentDayUnixTime))
            );
            $currentDayUnixTime = strtotime("+1 day", $currentDayUnixTime);
            $currentMonth = date('m', $currentDayUnixTime);
        }
        else {
            $arMonthDay[$weekIndex][$dayWeekIndex] = array(
                "day" => "",
                "today" => false
            );
        }

        if($dayWeekIndex == 7) {
            $weekIndex++;
            $dayWeekIndex = 1;
        }
        else {
            $dayWeekIndex++;
        }
    }
    if(!empty($arMonthDay[$weekIndex])) {
        $arMonthDay[$weekIndex] = array_pad($arMonthDay[$weekIndex], 7, array(
            "day" => "",
            "today" => false
        ));
    }
    return $arMonthDay;
}