PHP 获取年的第一天 和最后一天
if(empty($commitdate)) { $commitdate=date("Y-m-d"); }
$commitdate_month=date('m',strtotime($commitdate));
$commitdate_year=date('y',strtotime($commitdate));
$commitdate_day=date('d',strtotime($commitdate));
$commitdate_week=date('w',strtotime($commitdate));
...