#!/usr/bin/perl
use strict;
use warnings;

my $string1 = "Hello";
my $string2 = " World";
$string1 .= $string2;
print "$string1\n";

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

my $string1 = "Hello";
my $string2 = " World";
substr($string1,-1,0,"$string2");
print "$string1\n";