I consider the file1 and the file2 contents are equal numbers
use strict;
use warnings;
### open the first file and store in to a array format
open (F1, "file1.txt") || die "Cannot open the input file : $!";
my @file1=<F1>;
close (F1);
### open the second file and store in to a array format
open (F2, "file2.txt") || die "Cannot open the input file : $!";
my @file2=<F2>;
close (F2);
my @file3;
### process each element and store the file1 and the corresponding
### value in second file in another one array
for (my $i=0; $i<=$#file1; $i++)
{
chomp($file1[$i]);
push @file3, "$file1[$i]\t$file2[$i]";
}
### print the array in a output file
open (FOUT, ">Concat.txt") || die "Cannot create the output file";
print FOUT @file3;
close (FOUT);