#!/usr/bin/perl -w

use strict;

my %record;

while (my $line = <DATA>) 
{   
    $line =~ s/\s+$//; #see [cdarke]'s comment, this 
                       #also does chomp at same time
    $record{$line}=1  if ( $line ne ""); #comparison allows "zero"
    #$record{$line}++ if ( $line ne ""); #is also ok too. But I didn't
    				         #think that you needed count
}

my @record = sort keys %record;

#sort keys %record is a list and can just be assigned to an
#array variable, which appears to be what you want as result.
#note that in Perl, the identifier "record" can be used both as
#an array(@record) and as a hash(%hash).

print "@record"; #prints: a b c d
__DATA__
a

b
c

d

a
a
c

d
c