PHP: Multiple Unique Random Integers In A Specific Range - php

Question

I want to create 8 random integers, that are unique and in the range between 0 and 99.
Is there a neater solution, than the one that I thought of?
<?php
do {
$rnd1 = rand(0,99);
$rnd2 = rand(0,99);
$rnd3 = rand(0,99);
$rnd4 = rand(0,99);
$rnd5 = rand(0,99);
$rnd6 = rand(0,99);
} while (($rnd1 == $rnd2) ||
($rnd1 == $rnd3) ||
($rnd1 == $rnd4) ||
($rnd1 == $rnd5) ||
($rnd1 == $rnd6) ||
($rnd2 == $rnd3) ||
($rnd2 == $rnd4) ||
($rnd2 == $rnd5) ||
($rnd2 == $rnd6) ||
($rnd3 == $rnd4) ||
($rnd3 == $rnd5) ||
($rnd3 == $rnd6) ||
($rnd4 == $rnd5) ||
($rnd4 == $rnd6) ||
($rnd5 == $rnd6) );
?>

Answer 1

Try the code below.
It will create an array containing 8 random values between 0 and 99 while checking if they have been added already to ensure they are unique across.
$numbers = array();
while ( count($numbers) <= 8 ) {
$x = mt_rand(0,99);
if ( !in_array($x,$numbers) ) {
$numbers[] = $x;
}
}
print_r($numbers);
Also see these two Q&A's about using mt_rand vs. rand
Difference between mt_rand() and rand()
What's the disadvantage of mt_rand?

Answer 2

This is an optimized version that relies on the array indexes. The complexity of this solution is linear rather than n2 as in #AlexAndrei's answer. It relies on using array indexes as the guarantee there are no duplicates so there is no need to add the overhead of in_array.
$random_numbers = [];
do {
$rand = rand(0, 99);
$random_numbers[$rand] = $rand;
} while( count($random_numbers) < 9 );
$random_numbers = array_values($random_numbers); // This strips the keys
print_r($random_numbers);
If you are using a foreach you can even drop the array_values call which would also increase the speed of your code, but the numbers in the array will be in the form: [ a => a, b => b, ... ]

Answer 3

$rnds = [];
do {
$newRnd = rand(0, 99);
$rnds[] = $newRnd;
} while(in_array($newRnd, $rnds) && count($rnds) < 9);
print_r($rnds);