Question

What exactly is the difference between shuffle and array_rand functions in PHP? Which is faster if there is no difference.

Thanks

Answer 1

When called on an array, shuffle randomizes the order of all elements of that array.

For example, the following portion of code :

$arr = array(1, 2, 3, 4, 5);
shuffle($arr);
var_dump($arr);

Could give this output :

array
  0 => int 3
  1 => int 1
  2 => int 5
  3 => int 4
  4 => int 2

The whole array itself gets modified.

When called on an array, **[`array_rand`][2] returns one or more keys from that array, randomly selected**.

For example, the following portion of code :

$arr = array(1, 2, 3, 4, 5);
$randomly_selected = array_rand($arr, 3);
var_dump($randomly_selected);

Could give tis kind of output :

array
  0 => int 0
  1 => int 2
  2 => int 3

A sub-array of the initial array is returned — and the initial array is not modified.