use strict;
use warnings;

##</code><code>##

use autodie;

##</code><code>##

$data_type_number=@data_type_array;
for($i=0;$i<$data_type_number;$i++)
{
    ...
}

##</code><code>##

for (0 .. $#data_type_array) {
    ...
}

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;
use autodie;

use constant {
    FILENAME   => 0,
    FILEHANDLE => 1,
}; 

my %file = (
    animal => [ 'pm_1155794_animal.txt' ],
    plant  => [ 'pm_1155794_plant.txt' ],
    goods  => [ 'pm_1155794_goods.txt' ],
);

while (<DATA>) {
    my ($item, $type) = split;
    print { get_fh($type) } $item;
} 

sub get_fh {
    my $type = shift;

    open $file{$type}[FILEHANDLE], '>', $file{$type}[FILENAME]
        unless defined $file{$type}[FILEHANDLE];

    return $file{$type}[FILEHANDLE];
} 

__DATA__
cat animal
apple plant
strawberry plant
muffler goods

##</code><code>##

$ cat pm_1155794_animal.txt
cat
$ cat pm_1155794_plant.txt
apple
strawberry
$ cat pm_1155794_goods.txt
muffler