This "shuffles" the array, but not in a fair way. In fact, the algorithm contains two mistakes, a minor one and a severe one. Let's start with the minor one - in your loop you set $rand to rand $#array. But that means $rand could never be the last element of the array. However, fixing it that you take rand @array will not do you any good.

Let the size of the array be N. Then at each iteration, you select from N elements (after the fix given above), and change it with the one on position $i. You do this N times. Hence, you will get N^N different outcomes. There are however, only N! different permutations of the array. And since N! isn't a divisor of N^N for N > 2, some outcomes will be favoured over others by your algorithm.

Please use the Fisher-Yates shuffle as described in the FAQ. That one is fair.

Abigail