as_ndr has asked for the wisdom of the Perl Monks concerning the following question:

I have a complex hash: 
$db{worda}[0] = "stringa";
$db{worda}[1] = "stringb";
$db{worda}[2] = "stringc";
$db{wordb}[0] = "stringd";
$db{wordb}[1] = "stringe";
$db{wordc}[0] = "stringf";
$db{wordd}[0] = "stringg";
$db{worde}[1] = "stringh";
$db{worde}[2] = "stringi";
$db{worde}[3] = "stringj";

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but 500 times bigger. Is there a way to save it to a file and restore it later in only a few lines. The file doesn't have to be ledgible to the human eye. I just need a way to save and restore the data from the hash quickly and easily. Thanks!

Replies are listed 'Best First'.
Re: Saving and restoring hash variable data
by GrandFather (Saint) on Dec 08, 2005 at 23:39 UTC
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Re: Saving and restoring hash variable data
by Siddartha (Curate) on Dec 09, 2005 at 00:36 UTC
    Also have a look at Data::Dumper. Easiest way I have found to dump and restore most data structures. Has the added convenience of being human readable (As long as you understand Perl syntax).
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Re: Saving and restoring hash variable data
by TedPride (Priest) on Dec 09, 2005 at 01:54 UTC
    $rd is the record delimiter and $fd the field delimiter. Both must not be found in either keys or strings. I've used \n and \t for simplicity, but special characters or character sequences are probably smarter. 
    my $rd = "\n";
my $fd = "\t";

my %db;
$db{worda}[0] = "stringa";
$db{worda}[1] = "stringb";
$db{worda}[2] = "stringc";
$db{wordb}[0] = "stringd";
$db{wordb}[1] = "stringe";
$db{wordc}[0] = "stringf";
$db{wordd}[0] = "stringg";
$db{worde}[1] = "stringh";
$db{worde}[2] = "stringi";
$db{worde}[3] = "stringj";

for (keys %db) {
    print join $fd, $_, @{$db{$_}};
    print $rd;
}

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    And to reverse the generated data: 
    my $rd = "\n";
my $fd = "\t";

my (%db, $p, $i);

$/ = $rd;
while (<DATA>) {
    chomp; ($_, @_) = split $fd;
    $db{$_} = [@_];
}

for (sort keys %db) {
    $p = $db{$_};
    for ($i = 0; $i <= $#$p; $i++) {
        print "\$db{$_}[$i] = \"$p->[$i]\";\n";
    }
}

__DATA__
wordc    stringf
wordd    stringg
worde        stringh    stringi    stringj
worda    stringa    stringb    stringc
wordb    stringd    stringe

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Re: Saving and restoring hash variable data
by as_ndr (Initiate) on Dec 09, 2005 at 16:42 UTC
    Solution I am using: 
    use XML::Dumper;
my $dump = new XML::Dumper;

$db{worda}[0] = "stringa";
$db{worda}[1] = "stringb";
$db{worda}[2] = "stringc";
$db{wordb}[0] = "stringd";
$db{wordb}[1] = "stringe";
$db{wordc}[0] = "stringf";
$db{wordd}[0] = "stringg";
$db{worde}[1] = "stringh";
$db{worde}[2] = "stringi";
$db{worde}[3] = "stringj";

my $file = "dump.xml";
$dump->pl2xml( \%db, $file );
  
my %perl = $dump->xml2pl( $file );

print "New ref: $perl{worde}[3]\n";

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    I can't get the end part to work, though. Once the data is back into %perl, how to I access it correctly?
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Re: Saving and restoring hash variable data
by as_ndr (Initiate) on Dec 09, 2005 at 14:50 UTC
    Excellent! I will try out the suggestions now! Thanks for your help!
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