PHP - Generate random numbers with no duplicates

Question

I'm building an advent calendar in PHP 7 and want to show dates 1 - 24 in a random order.

I've got a jquery plugin which can randomise my div elements, but it's not very good, and I want to know how to do it in PHP.

My code to output the dates looks (in simplified terms) like this:

for ($d = 1; $d <= 24; $d++) {
    echo $d;
}

My plan was to instead use rand(1, 24) then store any numbers that had been generated in an array, e.g.

$date = rand(1, 24);
$used_dates[] = $date;

Then check $used_dates when picking a new date, e.g.

$unique_date = false;
while (!$unique_date) {
    $date = rand(1, 24);
    if (!in_array($date, $used_dates)) {
       $used_dates[] = $date;
       $unique_date = true;
    }
}

This seems inefficient though. Are there better ways?

piotr · Accepted Answer · 2016-11-25 12:44:34Z

10

In your case, you need create range array of numbers, and then simply shuffle them

$days = range(1,24);
shuffle($days);

Thats all

answered Nov 25, 2016 at 12:44

piotr

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RedLens834 · Accepted Answer · 2016-11-25 12:42:56Z

3

You can use shuffle() method.

Shuffle() take an array and order rows randomly.

$array = array("a", "b", "c");
shuffle($array);
// OUTPUT is random

answered Nov 25, 2016 at 12:42

RedLens834

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Ruslan Osmanov · Accepted Answer · 2016-11-25 12:44:15Z

3

$numbers = range(1, 24);
shuffle($numbers);

answered Nov 25, 2016 at 12:44

Ruslan Osmanov

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