How many different ways are there to concatenate two files line by line using Perl?

Question

Suppose file1 looks like this:

bye bye
hello
thank you

And file2 looks like this:

chao
hola
gracias

The desired output is this:

Answer 1

This works for any number of files:

use strict;
use warnings;
use autodie;

my @handles = map { open my $h, '<', $_; $h } @ARGV;

while (@handles){
    @handles = grep { ! eof $_ } @handles;
    my @lines = map { my $v = <$_>; chomp $v; $v } @handles;
    print join(' ', @lines), "\n";
}

close $_ for @handles;