In the CB, I presented:

for my $i (0..$#array) {
   for ($array[$i]) {
      ...
      if ($i == $#array) { ... }
      ...
   }
}
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Using this method, no change will be required to the body of your loop. $_ is still aliased to the array element as it normally is in a foreach loop. Changes to it will be reflected in the array.