Generate array of random unique numbers in PHP

Question

I\'m trying to generate an array of random numbers from 0-n then shuffle (but ensure that the keys and values DO NOT match).

For example:

0 => 3
1         


        

Answer 1

The approach here is to create a range of numbers from 0 to n, and then shuffle. We then look for key value matches, and swap pairs of them. If we don't have a pair to swap, we swap with the last item, unless the item is the last item, then we swap with the first.

Example shuffle when n is 5:

array (
  0 => 0,
  1 => 5,
  2 => 1,
  3 => 3,
  4 => 4,
  5 => 2,
)

Here we have matches for keys:

0, 3 and 4.

So we swap the values for keys 0 and 3, and 4 with the last.

array (
  0 => 3,
  1 => 5,
  2 => 1,
  3 => 0,
  4 => 2,
  5 => 4,
)

(array_key_first could be swapped for 0 given the range here. I've left it as it is more explicit.)