When I try to use $array[$i+1] -  $array[$i] I get use of uninitialized value in subraction.

This is probably a sign that you run $i across all valid indexes in your array -- which means that $i + 1 will be one past the end of the array, and thus uninitialized. If you are looking for adjacent differences, try this: 

  my @array = ( ... );
  my @adj_diff;
  for ( my $i = 0; $i < $#array; ++$i )
  {
      push @adj_diff, $array[$i+1] - $array[$i];
  }

[download]

This should result in @adj_diff having one fewer elements than @array. If you like the functional mode of programming, you could do it with a map too: 

  my @adj_diff = map { $array[$_+1] - $array[$_] } 0 .. $#array-1;

[download]

In reply to Re^2: Getting the next array element while still keeping the current one by tkil
in thread Getting the next array element while still keeping the current one by Anonymous Monk

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