继续生成随机数，直到一个不存在 - PHP

Question

I have a string with a lot of different numbers. I am trying to create a new random number and add it to the string.

The part I need help with is "if the number already exists in the string, create a new random number, and keep doing it until a number is created that does not yet exist in the string".

// $string contains all the numbers separated by a comma
$random = rand(5, 15);

$existing = strpos($string, $random);

if ($existing !== false) { $random = rand(5, 15); }

$new_string = $string.",".$random;

I know this isn't quite right as it will only check if it's existing once. I need it to keep checking to make sure the random number does not exist in the string. Do I use a while loop? How would I change this to work properly?

Your help is much appreciated.

Answer 1

A solution that works like Endijs ... but I want to post that :)

$string = '6,7,8';
$arr = explode(',', $string);

$loop = true;
while($loop) {
    $randomize = rand(5, 15);
    #var_dump($randomize);
    $loop = in_array($randomize, $arr);
    if (!$loop) {
        $arr[] = $randomize;
    }
}

$newString = implode(',', $arr);
var_dump($newString);