PHP small calendar class library

<?php
// file:calendar.class.php 日历类原文件
error_reporting(0);
class Calendar{
  private $year;
  private $month;
  private $start_weekday; //当月的第一天对应的是周几，作为当月开始遍历日期的开始
  private $days; //当前月总天数
//构造方法，用来初使化一些日期属性
  function __construct(){
//如果用户没有设置所份数，则使用当前系统时间的年份
    $this->year = isset($_GET["year"]) ? $_GET["year"] : date("Y");
//如果用户没有设置月份数，则使用当前系统时间的月份
    $this->month = isset($_GET["month"]) ? $_GET["month"] : date("m");
//通过具体的年份和月份，利用date()函数的w参数获取当月第一天对应的是周几
    $this->start_weekday = date("w",mktime(0,0,0,$this->month,1,$this->year));
//通过具体的年份和月份，利用date()函数的t参数获取当月的天数
    $this->days = date("t",mktime(0,0,0,$this->month,1,$this->year));
  }

Calendar is a daily-use publication used to record dates and other related information. One that displays information for one day on each page is called a calendar, one that displays information for one month on each page is called a monthly calendar, and one that displays information for a whole year on each page is called an annual calendar. There are many forms, such as wall calendars, desk calendars, annual calendar cards, etc., and now there are electronic calendars.

China first had a calendar about four thousand years ago. According to a page of the oracle bone calendar in the oracle bone inscriptions, it is proved that the calendar of the Yin Dynasty has reached a considerable level. This page of the oracle bone calendar is the oldest physical almanac in all mankind. This page of the oracle bone calendar is also called a calendar.