PHP array_rand function get repeat result

Question

I test php array_rand function and find it has repeat result ,this is my code:

    $arr = range(1,10000);
    $max = 200;
    $time = 0;
    while($time < $max){
        echo array_rand($arr).'<br>';
        $time++;
    }

And this is result:

You can see it keeps output repeat array index, and I am confused why it works like this, it is supposed to pick a random index.

Running the same code for me produces truly random data: 3v4l.org/t8bCd. You must have something else interfering. — Obsidian Age
– Obsidian Age, Commented Aug 25, 2017 at 2:45
I didn't have any repeating number either, but provided an answer that might work for you. — Brian Gottier
– Brian Gottier, Commented Aug 25, 2017 at 2:48
In 10000, you want to get 200 is not so good(large amount for that range) !! — Jack jdeoel
– Jack jdeoel, Commented Aug 25, 2017 at 2:58

Brian Gottier · Accepted Answer · 2017-08-25 02:46:11Z

1

You could make sure they don't repeat by doing something like this:

$arr = range(1,10000);
$max = 30;
$time = 0;
$used = array();
while($time < $max){
    $num = array_rand($arr);
    if( ! in_array($num, $used) ){
        echo $num . '<br>';
        $used[] = $num;
        $time++;
    }
}

answered Aug 25, 2017 at 2:46

Brian Gottier

4,6003 gold badges24 silver badges39 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jack jdeoel · Accepted Answer · 2017-08-25 03:28:54Z

0

You don't need to use while ! array_rand accept max random keys number as second parameter .

$arr = range(1,10000);
$max = 200;
$ran = array_rand($arr,$max);
var_dump($ran); // random keys
//tested with origin array $arr
//foreach($ran as $key) {
//    echo $arr[$key]."<br>"; 
//}

answered Aug 25, 2017 at 3:28

Jack jdeoel

4,5886 gold badges28 silver badges57 bronze badges

Comments

Lian · Accepted Answer · 2017-08-25 03:59:58Z

0

Because random values are not unique. Unless you really have to use numbers between 1 and 10,000, why not consider the following functions to get unique ids?

$number_and_letters = uniqid(); 
OR 
$numbers_only = hexdec(uniqid());

Hope it helps!

answered Aug 25, 2017 at 3:59

Lian

1138 bronze badges

Collectives™ on Stack Overflow

PHP array_rand function get repeat result

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related