1. Is it possible to write an array to disk in the same way as you can a hash, with either the dbmopen/dbmclose or that tiehash thing?

2. How can I sequentially step through elements in a hash? For example with an array I would just 'push' things on, then I 'shift' them off.

3. If I don't know the key from my hash, how can I just retrieve the first value?

For more info on hashes and arrays check out the official manpage on perl's data types, or pick up a copy of Learning Perl.
HTH

broquaint

my %hash = ('foo' => 'bar', 'bar' => 'foo');
my ($key, $val) = each(%hash);
print "$key\n";
[download]

2 & 3. A hash is not ordered, so there is no way to access the 'first' element. However, the keys( %hash ) function returns an array of the keys of a hash. This array is not ordered and calling keys repeatedly may or may not yield the same results. A common construct is to sort the keys before looping over the array; this will step through the hash in the alpabetical order of the keys, which is nearly but not really the same thing you are asking for in 2)

for my $key ( sort keys %myhash ) {
   print "$key: $myhash($key)\n";
}
[download]

Cheers,
--Moodster

1. I don't know if it is possible with dbmopen/dbmclose because I hardly use this

2. Yes, you can:

foreach my $key (keys %hash){
  print "$key => $hash{$key}\n";
}
# or shorter:
foreach (keys %hash){
  print "$_ => $hash{$_}\n";
}
[download]

while ( my ($key, $value) = each (%hash)){
  print "$key => $value\n";
}
[download]

shift, unshift, push or pop don't work with hashes; just add a hashelement with a new key, and it is about unshift or push:  $hash{newKey} = 'newValue';

3. get all keys with  my @keys = keys %hash; and choose which one you want... e.g. with: my $firstKey = ( keys %hash)[0];
Beware that hashes are not sorted, so getting the first key might not be exactly what you want. Or do you work with Tie::Hash?

Best regards,
perl -le "s==*F=e=>y~\*martinF~stronat~=>s~[^\w]~~g=>chop,print"

use Storable;
store (\@array, "/path/to/array.dat");
my @newarray = @{retrieve("/path/to/array.dat")};
[download]

while(<>) {
  /^(.+)\: (.+)$/;
  my $key = $1
  my @values = split(", ", $2);
  $hash{$key} = \@values;
}

foreach my $key (sort keys %hash) {
  print "$key:  ", join(", ", @{$hash{$key}}), "\n";
}
[download]