#!/usr/bin/perl

use strict;
use warnings;

### open(FILEIN, "table.txt"); #numbers table which only has 0 and 1.
### let's read from __DATA__ instead (try adding your own DATA...)

open FILEOUT, ">>data.txt" or die "data.txt: $!\n";
### opens data.txt in output/append mode

my @seed = split //, "01110011001111100010111101011111000100110";
my $expected = scalar @seed;

while (<DATA>) {  ### reads line by line from DATA which is provided below
    chomp;        ### you do want to chomp the input
    if ( ! /^[01]+$/ ) {
        warn "input line $. has characters other than 0 and 1\n";
        next;
    }
    my $length = length();
    if ( $length != @seed ) {
        warn "input line $. has $length digits instead of $expected\n";
    }
    my $count = 0;
    for my $digit ( split // ) {
        $seed[$count++] -= $digit;
    }

    print FILEOUT "@seed\n";  #shows you what we have read
}
### close FILEIN;
close FILEOUT;

__DATA__
01110011001111100010111101011111000100110
01110011001111100010111101011111000100110
1110011001111100010111101011111000100110
0011100110011111000101111010111110001001101
012345
xyz