PHP randomly generates random numbers that are not in a range

Idea: Store the generated random numbers in an array, and then remove duplicate values ​​in the array to generate a certain number of non-repeating random numbers.

In PHP website development, sometimes we need to generate a certain number of non-repeating random numbers within a specified range. How to specifically design this function to generate random numbers? We can store randomly generated numbers into an array, but by removing duplicate values ​​while storing them, a certain number of non-repeating random numbers can be generated.

You can also store the values ​​in the specified range into an array, then use shuffle($array) to disrupt the array, and then intercept a certain number of values. But the latter method will generate a larger array when the specified range of random numbers is too large.

The code for the first approach is given below, and the second approach is simpler.

<?php
/*
* array unique_rand( int $min, int $max, int $num )
* 生成一定数量的不重复随机数，指定的范围内整数的数量必须
* 比要生成的随机数数量大
* $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);
  }
  //打乱数组，重新赋予数组新的下标
  shuffle($return);
  return $return;
}

//生成10个1到100范围内的不重复随机数
$arr = unique_rand(1, 100, 10);
echo implode($arr, ",");
?>

Run results: 48,5,19,36,63,72,82,77,46,16
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