工作中用到的PHP函数

1.根据当前时间计算N天后的时间 $info = (new DateTime($nowDate))->add(new DateInterval("P{$days}D"))->format('Y-m-d’);2.根据一个指定的时间获取改天是周几$weekarray=array("日","一","二","三","四","五","六");echo "星期".$weekarray[date("w","2015-11-26")];3.二维数组排序$data = array(); $data[] = array('volume' => 67, 'edition' => 2); $data[] = array('volume' => 86, 'edition' => 1); $data[] = array('volume' => 85, 'edition' => 6); $data[] = array('volume' => 98, 'edition' => 2); $data[] = array('volume' => 86, 'edition' => 6); $data[] = array('volume' => 67, 'edition' => 7);  // 取得列的列表 foreach ($data as $key => $row) {     $volume[$key]  = $row['volume'];     $edition[$key] = $row['edition']; }  array_multisort($volume, SORT_DESC, $edition, SORT_ASC, $data);4.数组去重去空$newData = array_unique(array_filter($oldData));