PHP - Improve random number sequence generation

here comes my first question on SO.

I'm currently working on a website and I have to generate 6 numbers between 1 and 29 (one of each max) for a lottery. As they can be in any order, I simply sort them afterwards.

If I'm not mistaken, it should mean that there's (29*28*27*26*25*24) / 6! = 475020 different possible combinations.

I've tried different ways of genereting the sequences, either using mt_rand or random_int (from random_compat) but when I test it with something like 10k iterations, I always get around 100 duplicates, even though they are like 465k combinations still available.

Here are the code samples I've been trying :

// Using an array and mt_rand (or random_int, giving same results)
// Also tried shuffling the array instead of simply reindexing it, not better

$values = range(1, 29);

while(count($values) > 6) {
    unset($values[mt_rand(0, count($values) - 1)]);
    $values = array_values($values);
}



// Creating the array from random numbers (same results using random_int)

$values = array();
while (count($values) < 6) {
    $r = mt_rand(1, 29);
    if (in_array($r, $values)) {
        continue;
    } else {
        $values[] = $r;
    }
}

So well... My questions are :

• Is there a way to improve what I'm currently doing ?
• Is that the way it's gonna be and I have to deal with it ?
• Am I simply doing it wrong ?

Thanks !

Lyn.

PS : Looked through many questions, but didn't find anything filling my needs, sorry if I didn't look well enough !