PHPで100個の異なる乱数を生成する方法

<?php
/*
* array unique_rand( int $min, int $max, int $num )
* 生成一定数量的不重复随机数
* $min 和 $max: 指定随机数的范围
* $num: 指定生成数量
*/
function unique_rand($min, $max, $num) {
  $count = 0;
  $return = array();
  while ($count < $num) {
      $return[] = mt_rand($min, $max);
      $return = array_flip(array_flip($return));
      $count = count($return);
  }
  shuffle($return);
  return $return;
}
$arr = unique_rand(1, 1000, 100);
sort($arr);
$result = &#39;&#39;;
for($i=0; $i < count($arr);$i++)
{
  $result .= $arr[$i].&#39;,&#39;;
}
$result = substr($result, 0, -1);
echo $result;
?>

5,14,36,59,61,65,70,72,95,103,105,114,124,138,142,143,153,159,170,174,175,184,186,189,207,210,214,220,254,256,257,259,268,273,280,281,290,293,295,303,309,315,316,321,327,359,364,370,416,420,429,433,434,436,438,449,464,493,505,558,563,568,570,593,599,637,639,646,656,659,670,687,695,709,713,719,722,731,733,736,749,750,784,803,807,812,835,849,859,893,899,914,937,941,948,951,960,969,991,992