$ perl -Mstrict -Mwarnings -E '
my @array = (
   q{Hello, my name is John},
   q{How are you?},
   q{blah (blah)},
   );
my $byteCt = 0;
do {
   my $len = length;
   s{^}{ sprintf q{%08d }, $byteCt }e;
   $byteCt += $len;
   } for @array;
say for @array;'
00000000 Hello, my name is John
00000022 How are you?
00000034 blah (blah)
$