Generate array of random unique numbers in PHP

This will generate an array with 10 random numbers from 0 to 100:

array_map(function () {
       return rand(0, 100);
   }, array_fill(0, 10, null));

Result:

array(10) {
  [0]=>
  int(15)
  [1]=>
  int(97)
  [2]=>
  int(20)
  [3]=>
  int(64)
  [4]=>
  int(57)
  [5]=>
  int(38)
  [6]=>
  int(16)
  [7]=>
  int(53)
  [8]=>
  int(56)
  [9]=>
  int(22)
}

Explanation:

• array_fill(0, 10, null) will generate an array with 10 empty items
• array_map Applies the callback (first argument) to each item of the array it receives (second argument). In this example, we just return a random number for each array item.

Playground: https://3v4l.org/FffN6

If you need to make sure each generated number is unique:

$uniqueNumbers = 100;
$picked = [];
$uniqueRandomNumbers = array_map(function () use(&$picked, $uniqueNumbers) {
    do {
      $rand = rand(0, $uniqueNumbers);
    } while(in_array($rand, $picked));

    $picked[] = $rand;

    return $rand;
}, array_fill(0, $uniqueNumbers, null));

https://3v4l.org/mSWBo#v8.0.9

$max = 5;
$done = false;
while(!$done){
    $numbers = range(0, $max);
    shuffle($numbers);
    $done = true;
    foreach($numbers as $key => $val){
        if($key == $val){
            $done = false;
            break;
        }
    }
}

A even shorter solution:

$random_number_array = range(0, 100);
shuffle($random_number_array );
$random_number_array = array_slice($random_number_array ,0,10);

print_r($random_number_array);

Result will be:

[0] => 53
[1] => 6
[2] => 16
[3] => 59
[4] => 8
[5] => 18
[6] => 62
[7] => 39
[8] => 22
[9] => 26