Roy Johnson's solution works, but it is not warning free. The original problem seems to me to scream out for the use of a hash. Here is how I would have approached the problem:
use strict;
use warnings;

print "Content-type: text/html\n\n";

my %someData;

while(<DATA>)
   {
   chomp();
   (my $key, my $value) = split(/\|/, $_, 2);
   $someData{$key} = $value;
   }

foreach (sort { $a <=> $b } keys %someData)
   {
   print "$_\{$someData{$_}\}\n";
   }

__DATA__
30|microsoft
70|aol
76|netscape
5|trouble?
35|mozilla
40|opera
100|FireFox

[download]

In reply to Re^2: How can I sort this data on the first field by NateTut
in thread How can I sort this data on the first field by Anonymous Monk

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