use Devel::Peek;

my $v = "\x{00}";  # $v is a string with a NUL character
Dump $v;

__END__
SV = PV(0x100801c78) at 0x1008143e8
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x100218910 "\0"\0
  CUR = 1
  LEN = 8