How can I store simple hash in perl using data dumper - perl

Question

%hash = ('abc' => 123, 'def' => [4,5,6]);
how can I store above hash in file using data dumper in Perl

Answer 1

Files can only contain sequences of bytes, so you need to convert the data structure into a sequence of bytes somehow. This process is called serialization.
The possibilities available to you are endless, but a few are worth mentioning:
JSON is a very common choice.
YAML is more flexible.
Storable is specifically made for Perl data structures.
There is also Data::Dumper, as you say.
use Data::Dumper qw( );
sub serialize {
my ($x) = #_;
local $Data::Dumper::Purity = 1; # Required for some data structures.
local $Data::Dumper::Useqq = 1; # Optional. Limits output to ASCII.
local $Data::Dumper::Sortkeys = 1; # Optional. Makes revision control easier.
return Data::Dumper->Dump([$x], ["x"]);
}
print($fh serialize($x));
Data::Dumper isn't a particularly good choice, since there's no existing module to safely deserialize the structure in Perl[1], and there's even less support outside of Perl.
sub deserialize {
my ($s) = #_;
my $x;
eval($s); # XXX Unsafe!
die($#) if $#;
return $x;
}
If you're ok with limiting yourself to data structure JSON can serialize (by setting Purity to 0), then you could use Data::Undump to safely deserialize. But then why not just use JSON?!

Answer 2

use Data::Dumper
open (FL, ">", "file.txt") or die "Cant open file $! ";
print FL Dumper \%hash;
close FL;

Answer 3

"how can I store above hash in file using data dumper in Perl"
Store it as JSON so it can be read back by (almost) anything, using Data::Dumper configured to print JSON.
use strict;
use warnings;
use Data::Dumper;
local $Data::Dumper::Pair = ' : ';
local $Data::Dumper::Quotekeys = 1;
local $Data::Dumper::Useqq = 1;
local $Data::Dumper::Terse = 1;
my %hash = ('abc' => 123, 'def' => [4,5,6]);
open my $file, '>', 'foo.json' or die $!;
print $file Dumper \%hash;
Output:
$ cat foo.json
{
"def" : [
4,
5,
6
],
"abc" : 123
}
(Note: I would of course rather use a dedicated JSON-handling module for this, but you asked ....)