PHP日历的算法

 1 <?php
 2 if (function_exists(‘date_default_timezone_set‘)) {
 3     date_default_timezone_set(‘Asia/Chongqing‘);
 4 }
 5 $date = isset($_GET[‘date‘]) ? $_GET[‘date‘] : date(‘Y-m-d‘);
 6 $date = getdate(strtotime($date));
 7 $end = getdate(mktime(0, 0, 0, $date[‘mon‘] + 1, 1, $date[‘year‘]) - 1);
 8 $start = getdate(mktime(0, 0, 0, $date[‘mon‘], 1, $date[‘year‘]));
 9 $pre = date(‘Y-m-d‘, $start[0] - 1);
10 $next = date(‘Y-m-d‘, $end[0] + 86400);
11 $html = ‘<table border="1">‘;
12 $html .= ‘<tr>‘;
13 $html .= ‘<td><a href="‘ . $PHP_SELF . ‘?date=‘ . $pre . ‘">-</a></td>‘;
14 $html .= ‘<td colspan="5">‘ . $date[‘year‘] . ‘;‘ . $date[‘month‘] . ‘</td>‘;
15 $html .= ‘<td><a href="‘ . $PHP_SELF . ‘?date=‘ . $next . ‘">+</a></td>‘;
16 $html .= ‘</tr>‘;
17 $arr_tpl = array(0 => ‘‘, 1 => ‘‘, 2 => ‘‘, 3 => ‘‘, 4 => ‘‘, 5 => ‘‘, 6 => ‘‘);
18 $date_arr = array();
19 $j = 0;
20 for ($i = 0; $i < $end[‘mday‘]; $i++) {
21     if (!isset($date_arr[$j])) {
22         $date_arr[$j] = $arr_tpl;
23     }
24     $date_arr[$j][($i+$start[‘wday‘])%7] = $i+1;
25     if ($date_arr[$j][6]) {
26         $j++;
27     }
28 }
29 foreach ($date_arr as $value) {
30     $html .= ‘<tr>‘;
31     foreach ($value as $v) {
32         if ($v) {
33             if ($v == $date[‘mday‘]) {
34                 $html .= ‘<td><b>‘ . $v . ‘</b></td>‘;
35             } else {
36                 $html .= ‘<td>‘ . $v . ‘</td>‘;
37             }
38         } else {
39             $html .= ‘<td> </td>‘;
40         }
41     }
42     $html .= ‘</tr>‘;
43 }
44 $html .= ‘</table>‘;
45 echo $html;
46 ?>