#!/usr/bin/perl

use strict;

my @a = qw( a
b
c
d );

my @z;
for (@a) {
    chomp;
    s/(d)/new(\1)/;
    push ( @z, $_ );
}

print join ",", @z;

##</code><code>##

a ,b ,c , new(d)

##</code><code>##

print join ", ", map { chomp; s/(d)/new(\1)/ } @a;