array_rand returning incorrect value from array

Question

I'm having a problem when using array_rand.

The thing is that I called some values from my database into an array, and then I did array_rand to randomly select one of those values (you don't say).

$query = mysqli_query($con,"SELECT * FROM random");

while ($row = mysqli_fetch_assoc($query)) {
    $num[] = $row["id"];
}

If I do a print_r($num);, I get the following:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
    [6] => 7
    [7] => 8
    [8] => 9
    [9] => 10
    [10] => 11
    [11] => 12
    [12] => 13
    [13] => 14
)

But when doing array_rand($num);, one of the values that I randomly get is 0, which as you can see, is not in the list, therefore the rest of the code that uses this random value won't work if it cames up with it.

I searched in Google for this problem, but couldn't find a solution, I'm sorry if this has been mentioned before.

Hopefully you can help me fix this problem.

Thanks in advance.

xdazz · Accepted Answer · 2014-02-13 02:42:26Z

2

As the document said, array_rand() returns the key for a random entry.

So you have to do with $num[array_rand($num)] to get the value.

answered Feb 13, 2014 at 2:42

xdazz

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1 Comment

user2077474 Over a year ago

Oh I see, any other function that I could use?

Marty · Accepted Answer · 2014-02-13 02:52:11Z

1

In this case, why not use RAND() in your query and save some work & resources?

$query = mysqli_query($con, "SELECT * FROM random ORDER BY RAND() LIMIT 1");
$result = mysqli_fetch_object($query);

edited Feb 13, 2014 at 2:52

answered Feb 13, 2014 at 2:46

Marty

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2 Comments

user2077474 Over a year ago

Yup, thanks. I'm kinda new to PHP + MySQL and I keep forgeting that I can do this stuff with MySQL.

Marty Over a year ago

@user2077474 I've only recently started getting comfortable with MySQL - I used to leave a lot up to PHP as well (anything other than basic sorting, joining data, etc). You'll be surprised by how much MySQL can be responsible for.

Krease · Accepted Answer · 2014-02-13 02:44:44Z

0

From the documentation of array_rand (emphasis added):

Picks one or more random entries out of an array, and returns the key (or keys) of the random entries.

0 is the key of your first element being returned

answered Feb 13, 2014 at 2:44

Krease

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