用PHP函数知识来实现年历的制作

以下是一个简单的PHP函数来制作年历：

function createCalendar($year) {
  // 设置每个月的天数
  $daysInMonth = array(31, 28 + isLeapYear($year), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

  // 设置月份和星期几的名称
  $months = array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");
  $daysOfWeek = array("Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat");

  // 用表格形式输出日历
  echo "<table>";

  // 输出年份
  echo "<tr><th colspan='7'>$year</th></tr>";

  // 循环输出每个月的日历
  for ($month = 0; $month < 12; $month++) {
    // 输出月份名称
    echo "<tr><th colspan='7'>$months[$month]</th></tr>";

    // 输出星期几的名称
    echo "<tr>";
    foreach ($daysOfWeek as $day) {
      echo "<td>$day</td>";
    }
    echo "</tr>";

    // 输出日期
    $date = mktime(0, 0, 0, $month + 1, 1, $year);
    $dayOfWeek = date("w", $date);
    $numDays = $daysInMonth[$month];
    $dayCount = 1;

    echo "<tr>";
    for ($i = 0; $i < $dayOfWeek; $i++) {
      echo "<td></td>";
    }
    while ($dayCount <= $numDays) {
      if ($dayOfWeek == 7) {
        echo "</tr><tr>";
        $dayOfWeek = 0;
      }
      echo "<td>$dayCount</td>";
      $dayCount++;
      $dayOfWeek++;
    }
    while ($dayOfWeek != 7) {
      echo "<td></td>";
      $dayOfWeek++;
    }
    echo "</tr>";
  }
  echo "</table>";
}

// 判断是否是闰年
function isLeapYear($year) {
  return ($year % 4 == 0 && $year % 100 != 0) || $year % 400 == 0;
}

// 调用函数
createCalendar(2022);

这个函数会创建一个包含指定年份所有月份的日历表格。它使用了date()函数来获取每个月份的第一天是星期几，然后使用循环和条件语句来输出日期。