#! perl
use Modern::Perl;
use Data::Dump;

my @array1 =
(
     undef,
     undef,
    'abcd',
    'efgh',
     undef,
     undef,
    'jklm',
    'nopq',
     undef,
     undef,
);

my @array2 = split /\0\0/, join('', map { $_ // "\0" } @array1);
   @array2 = @array2[1 .. $#array2] unless $array2[0];    

dd @array1;
dd @array2;

##</code><code>##

21:38 >perl 508_SoPW.pl
(
  undef,
  undef,
  "abcd",
  "efgh",
  undef,
  undef,
  "jklm",
  "nopq",
  undef,
  undef,
)
("abcdefgh", "jklmnopq")

21:38 >

##</code><code>##

map { $_ // "\0" } @array1

##</code><code>##

map { $_ || "\0" } @array1

##</code><code>##

map { $_ eq '' ? "\0" : $_ } @array1