# Assume a FIELD#...# string can't be split across lines.
use strict;
use warnings;

use Data::Dumper;


my @DATA_FIELDS = (
    'TITLE',
    'DATA-A', 
    'DATA-B',
    'DATA-C',
);

# Build a regex that matches all fields and extracts a value.
my $all_fields = join '|', @DATA_FIELDS;
my $DATA_REGEX = qr/($all_fields)#([^#]*)#/;


my @data;               # store all tag data
my $title_data = {};    # reference to current title's data store.

while (<DATA>) {
    
    # the /g
    while ( /$DATA_REGEX/g  ) {
        my $field = $1;
        my $value = $2;

        print "$_ -> $field, $value\n";
    
        if( $field eq 'TITLE' ) {

            # store previous title data set if not empty.
            push @data, $title_data
                if %$title_data;

            # start new title data set
            $title_data = { TITLE => $value };
        } 
        else {
            # store field data in current title data set.
            push @{ $title_data->{$field} }, $value;
        }
    }
    
}

# store final title data set
push @data, $title_data
    if %$title_data;

print Dumper \@data;


__DATA__


asdf
asdfg=4eafvasdfadsf
ashfasdf
asdf qer qwer
asd as dsasdi weeiwer dfhjTITLE#How are you#asdfads
asdfa

asdg
rt
wqrqw
re

DATA-A#item1#asdfdasfdasdasDATA-B#item2#
asdfda
dasfa


asdfdas
DATA-C#item3#
aasdfDATA-A#item1a#DATA-B#item2b#

asd
asdf
asdDATA-C#item3c#
asdf asdf3132 adsf TITLE#I am fine#ads fadsfdasfdas