use strict;
use warnings;

use Data::Dumper;

use Tie::File;

# open the file if it exists, but fail if it does not
use Fcntl 'O_RDWR';

our @array = ();

our $file = 'taste';

tie @array, 'Tie::File', $file, mode => O_RDWR or die $!;

our $SearchString = 'HAI WORLD Times ([0-9]+).*$';
#our $ReplaceString = "\t\t<exML LOLZ = \"" . unpack('a1', $1) . '"/>'; # we could use such a statement ONLY if we figured out what something() would be

my $elementIdx = 0;

while($elementIdx <= $#array)
{
	if($array[$elementIdx] =~ $SearchString)
	{
		# Maintain only the first character
		
		#$array[$elementIdx] = unpack ('a' . (1 + length("\t\t<exML LOLZ = \"\"/>")), something($ReplaceString)); # I would love to know what something() could be so that I can separate the configuration from the logic  
		$array[$elementIdx++] = "\t\t<exML LOLZ = \"" . unpack('a1', $1) . '"/>';
		#++$elementIdx;
	}
	else
	{
		splice @array, $elementIdx, 1;
		# we don't want this in the output
	}
}

untie @array;	# all done!