PHP取得隨機時間的函數

<?php
// 取得隨機時間的函數
function get_rand_time($st_time, $ed_time)
{  
  $nums = ($ed_time - $st_time)/(24*60*60);
  //echo  '1 ~ ' . $nums . '<br/>';

  $rd_num = rand(1,$nums);
  //$rand_time = $st_time + ($rd_num - 1) * 24*60*60;
  $rand_time = $st_time + ($rd_num - 1) * 24*60*60 + (rand(1,86399));
  if($rand_time > time()) $rand_time = time();
  //echo $rand_time . ' ('.$rd_num.') <br/>';
  //echo date("Y-m-d H:i:s", $rand_time);
  
  return date("Y-m-d H:i:s", $rand_time);
}

// 執行函式呼叫
$ed_time = strtotime(date("Y-m-d"));
$st_time = $ed_time - 30*24*60*60;

get_rand_time($st_time, $ed_time);

?>