Seems to me it's much more simple to just (mostly pseudo-code)
# open FILE1 and FILE2

my ($f1, $f2);

while (($f1 = <FILE1>) && ($f2 = <FILE2>) {
  # split and subtract and print with $f1 and $f2 as in other suggesti
+ons.
}

# close all.

[download]
This way, while you do have two (probably three, with the printing and all) filehandles open, you don't have to slurp any of them.

In reply to Re: hash or nest loop by Jasper
in thread hash or nest loop by Anonymous Monk

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