If you are expecting the statement ... to interchange the elements, you are missing a step or two.
No, that part works fine:
my @usernames = qw(zero one two three four five six);
testswap(\@usernames);
print join(" ", @usernames), "\n";
sub testswap {
my $array = shift;
my $i = 2;
my $j = 5;
@$array[$i, $j] = @$array[$j, $i];
}
Prints:
zero one five three four two six
As runrig pointed out, you're not returing a value, you could put return $array->[0] at the end of the subroutine.
If you just want to pick one element out of the list, you're going to too much trouble. You can just say:
my $username = $usernames[rand(@usernames)];
