PHP function, add random unique numbers to an array that match a certain value

Question

Im trying to build an function that adds 5 unique numbers that match a certain value.

My snippet below does not always add 5 numbers, and it needs to be 5 unique values.

$random = [];
$val    = 22;// this will be random every time
$fields = 100;
$total  = 5;
for ($i = 1; $i <= $total; $i++) {
    $r = rand(1,$fields);                 
    if(!in_array($r, $random) && $r !== $val){
        $random[] = $r;
    }
}
return $random;

That's because you run your loop for exactly 5 times, but you're not guaranteed to add an item in every iteration. You should rather create a loop that goes on until you have 5 results. — El_Vanja
– El_Vanja, Commented Apr 26, 2021 at 9:55

Eliran Givoni · Accepted Answer · 2021-04-26 13:39:20Z

1

Create do...while loop and rand as times as possible if value is already exists in the random array.

        $random = [];
        $val    = 22;// this will be random every time
        $fields = 100;
        $total  = 5;

        for ($i = 1; $i <= $total; $i++) {
            do {
                $r = rand(1, $fields);
            } while(in_array($r, $random) || $r === $val);

            $random[] = $r;
        }

        var_dump($random);

answered Apr 26, 2021 at 13:39

Eliran Givoni

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1 Comment

El_Vanja Over a year ago

It seems a bit of an overkill to use nested loops. A do ... while should be sufficient.

Tigger · Accepted Answer · 2021-04-27 10:23:37Z

0

A single do ... while loop with a check is all that is required.

Personally, I would use mt_rand() over rand() for legacy reasons, but from PHP 7.1.0 onward, rand() uses the same math as mt_rand().

$random = [];
$val = 22; // this will be random every time
$fields = 100;
$total = 5;
do {
    $r = mt_rand(1,$fields);
    if (($r != $val) && (! in_array($r,$random))){
        $random[] = $r;
        $total--;
    }
} while($total);

var_dump($random);

Sample result:

array(5) {
  [0]=>int(56)
  [1]=>int(29)
  [2]=>int(96)
  [3]=>int(92)
  [4]=>int(79)
}

answered Apr 27, 2021 at 10:23

Tigger

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