Thanks guys. But now I come up with one more question. Now I want to print all the lines sorted by the Town. Like this 
Town         Surname       Firstname

Basel        Chaplin       Charlie          
Manica       Estevez       Emilio Santa   
Montmarte    Sarte         Jean Paul  
Montmarte    Rodin         Paul 
Amsterdam    Rikard        Frank

[download]
I did something like this: 
my $data = "clients.dat";
open (DAT, $data) or die "\"$data\" not existed or can't be opened!\n"
+;
my @client;  # make this an array, not a hash;
my @fields = qw/surname firstname town/;

while (<DAT>) {
    next if ( /^Surname/ or /^-/ );
    my @values = unpack 'A20A20A20', $_;
    my %entry = map { $fields[$_] => $values[$_] } ( 0..$#fields );
    push @client, \%entry;
}

my @towns;
my $client;
foreach my $client (@client){
    push @towns, "$client->{'town'}";
}
my @sorted_towns = sort @towns;

foreach my $key (@sorted_towns) {
    my @elems = $key;
    my $client = $client->[$elems[1]-1];
    print "$client->{'town'} $client->{'surname'} $client->{'firstname
+'}";
    
}

[download]
But this doesnt work somehow. Can anyone help please?

In reply to Re^2: How to read data file into an array of hashes by fseng
in thread How to read data file into an array of hashes by fseng

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