use Devel::Peek;

 my $dd = "hello world\n";
 Dump $dd;
#output:
SV = PV(0x55608d816050) at 0x55608d83a0a8
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x55608d8b8e90 "hello world\n"\0
  CUR = 12
  LEN = 14
  COW_REFCNT = 1

##</code><code>##

my $dd = "hello world\n";
printf("the dd string address is %x \n", cc($dd));
use Inline 'C' => <<'CODE';
 unsigned int cc(SV* a){
 40 return SvPVX(a);
 41 }
 42 CODE

# just print the dd string address is 8d8b8e90, the upper 4bytes of the address was truncated.