php返回相对时间（如：20分钟前，3天前）的方法

 1 function plural($num) {
 2  if ($num != 1)
 3   return "s";
 4 }
 5 function getRelativeTime($date) {
 6  $diff = time() - strtotime($date);
 7  if ($diff<60)
 8   return $diff." 秒".plural($diff)." 前";
 9  $diff = round($diff/60);
10  if ($diff<60)
11   return $diff." 分钟".plural($diff)." 前";
12  $diff = round($diff/60);
13  if ($diff<24)
14   return $diff." 小时".plural($diff)." 前";
15  $diff = round($diff/24);
16  if ($diff<7)
17   return $diff." 天".plural($diff)." 前";
18  $diff = round($diff/7);
19  if ($diff<4)
20   return $diff." 星期".plural($diff)." 前";
21  return "on ".date("F j, Y", strtotime($date));
22 }