简单的PHP日历算法

/**
* 日历
*
* Copyright(c) 2007 by 陈毅鑫(深空). All rights reserved
* To contact the author write to {@link mailto:shenkong@php.net}
* @author 陈毅鑫(深空)
*/
if (function_exists('date_default_timezone_set')) {
date_default_timezone_set('Asia/Chongqing');
}
$date = isset($_GET['date']) ? $_GET['date'] : date('Y-m-d');
$date = getdate(strtotime($date));
$end = getdate(mktime(0, 0, 0, $date['mon'] + 1, 1, $date['year']) - 1);
$start = getdate(mktime(0, 0, 0, $date['mon'], 1, $date['year']));
$pre = date('Y-m-d', $start[0] - 1);
$next = date('Y-m-d', $end[0] + 86400);
$html = '