php 寫了一個Calendar，但當要跨年份的時候就不行了！

Question

$date = strtotime(date("Y-m-d")); $day = date('d', $date); $month = str_pad($_GET['m'],2,'0',STR_PAD_LEFT); $year = date('Y', $date); $firstDay = mktime(0,0,0,$month, 1, $year); $title = strftime('%m', $firstDay); $dayOfWeek = date('D', $firstDay); $daysInMonth = cal_days_in_month(0, $month, $year); $timestamp = strtotime('next Sunday'); $weekDays = array('日', '一', '二', '三', '四', '五', '六'); for ($i = 0; $i < 7; $i++){ $timestamp = strtotime('+1 day', $timestamp); } $blank = date('w', strtotime("{$year}-{$month}-01")); <td><?if($_GET['m']!='01'){?><a class="monthLink" href="?m=<?=str_pad($month-1,2,'0',STR_PAD_LEFT);?>&y=<?=$year;?>&region=<?=$_GET['region'];?>">← <?=$month-1;?>月</a><?}?></td> 我是用<?=$month-1;?> 或 <?=$month+1;?>來讓用戶選月份但是到了01月的時候會變成00月如能讓他能往上一年的十二月開始選？以及往下一年的一月開始選？而不會有盡頭

Answer 1

if($month == 0)
{
    $year--;
    $month = 12;
}
if($month == 13)
{
    $year++;
    $month = 1;
}