I'm not sure why chromatic seemed to miss the boat on this one. Although I might be wrong, it would seem that the linefeed ("\n") is being left on the fourth element of the array. Maybe a rushed posting. Here's a more compacted version: 
my @output = sort { $a->[0] cmp $b->[0]
                 || $a->[3] <=> $b->[3] }
             map { chomp; [ split(',', $_, 4) ] }
             <INPUT_FILE>;

[download]
Remember that with this kind of structure the data flows from the bottom up. From the file, through the map which makes the proper array-of-arrays (AoA), and in to the sort routine which re-orders it before storing the result in @output.

As a note, though, comparing phone numbers numerically is pretty lacking. If one has a dot and the other a dash, your sort is going to be ruined. Here's a more robust version that only sorts the numerical component of the phone number, ignoring brackets, dashes and the like: 
sub phone_value
{
     my ($v) = @_;
     $v =~ tr/^0-9//d;
     return $v;
}

my @output = sort { $a->[0] cmp $b->[0]
                 || phone_value($a->[3]) <=> phone_value($b->[3]) }
             map { chomp; [ split(',', $_, 4) ] }
             <INPUT_FILE>;

[download]

In reply to Re: How do you specify which fields to sort by when sorting an array. by tadman
in thread How do you specify which fields to sort by when sorting an array. by brentheigold

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