ybiC,

I think you want to look at an if exists statement for your hash. It will look at a primary key and return true if it exists. As for the sort, you are on your own for that, I haven't needed to learn that function yet. %^) Update: Posted this code per ybiC's request. Here is some code I pieced together that compared two files into a hash.

#!/usr/bin/perl -w

use strict;
use diagnostics;

my $file1 = "/home/scott/PerlHacks/post.office/file1";
my $file2 = "/home/scott/PerlHacks/post.office/file2";
my $hashOfLists;
my %hashOfLists;

open (FILE1, "$file1") or die "Could not open $file1 $!";
open (FILE2, "$file2") or die "Could not open $file2 $!";


######################################################
#####This block reads all of the items of the file into
#####a hash with the item being the key. Since I
##### was comparing 2 files each key received a
#####value of 1 if it was in the first file, 2 if
#####it was in both , and 3 if it was only in file 2
######################################################

foreach (<FILE1>)
{
chomp $_;
$hashOfLists{$_} =1;
}


foreach (<FILE2>)
{
chomp $_;
######################################################
#####if exists checks the hash to see if $_ exists.
##### If true $_'s value becomes 2,
#####if false, $_ gets a value of three ##############################
+########################
if (exists $hashOfLists{$_})
{
($hashOfLists{$_}) =2;
}
else
{
($hashOfLists{$_})=3;
}
}


close FILE1 or die "Could not close $file1 $!";
close FILE2 or die "Could not close $file2 $!";
[download]

"The social dynamics of the net are a direct consequence of the fact that nobody has yet developed a Remote Strangulation Protocol." -- Larry Wall

Edited by planetscape - added code tags