There is Yet Another Reason why you really don't want to magicalize the adding operator, and that is the way it handles alphanumeric characters. E.g., 'z9' with ++ becomes 'aa0'. What would you want to do with 'z9' + 'a04'? That promises to get unbelievable messy. And we even haven't touched the subject of fractions... I suggest you leave the magic alone and use sprintf instead. 
sub format_add{
  my ($x, $y) = @_;
  my $ret = $x + $y;
  my $digs = length $x;
  sprintf("%0${digs}d", $ret );
}

[download]
Of course you can overload the '+' with this sub.

The ++ can do some strange things, by the way: 
  $a=0.5;    print ++$a; #prints 1.5
  $a='a0.5'; print ++$a; #prints a6 
     #(so ++ ignores the dot and squashes the 0)
  $a='2a';   print ++$a; #prints 3 
     #(because 2a in numeric context returns 2)

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Apparently it is a beast to handle with care.

Jeroen
"We are not alone"(FZ)

In reply to Re: Squeezing $a+1 to be magical like $a++ by jeroenes
in thread Squeezing $a+1 to be magical like $a++ by coolmichael

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