First of all change 
while (<TEST>) {
  my ($key,@fileData) = split /\|/;
  chomp @fileData;
  $test{$key} = \@fileData;
}
#to
while (<TEST>) {
  chomp;
  my ($key,@fileData) = split /\|/;
  $test{$key} = \@fileData;
}

[download]
Otherwise you are chomping every item in the array, when you know there can only be a newline at the end of the line.

I would change 

foreach my $key (keys %test) {
      push (@sorted, "$key|$test{$key}->[0]|$test{$key}->[1]|$test{$ke
+y}->[2]|$test{$key}->[3]");
}
#to 
foreach my $key (keys %test) {
      push @sorted, (join '|', ($key,@{$test{$key}});        
}

[download]
except that that is overkill... since you can't have the multiples of the same key, you don't need to sort on the whole line, just the key, I would do... 
open(TEST, ">test.txt") || die "File couldn't be opened for writing: $
+!";
foreach my $key (sort keys %test) {
  print TEST (join '|', ($key,@{$test{$key}});
  print TEST "\n";
} 
close(TEST);

[download]
Instead of the whole @sorted thing

Update Sorry, you wanted to sort by the last item in the array of data... change 

foreach my $key (sort keys %test) {
#to
foreach my $key (sort { $test{$a}[-1] <=> $test{$b}[-1] } keys %test) 
+{

[download]
the $test{$a}[-1] <=> $test{$b}[-1] sorts numerically based on the final item in the data array at each key
Untested, but I believe it all works fine

                - Ant

In reply to Re: Learning to use the hash effectively by suaveant
in thread Learning to use the hash effectively by Stamp_Guy

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