$ perl new.pl
SV = PV(0x7460) at 0x35cb4
  REFCNT = 1
  FLAGS = (TEMP)
  PV = 0x6330 " \0w.pl\0\0\0\0"\0
  CUR = 10
  LEN = 11

##</code><code>##

use Devel::Peek;
use Inline C=> 'DATA';

Dump(foo( 10 ));

sub vis { map { join '', map sprintf("\\%o", ord), split // } @_ }

__DATA__
__C__
SV* foo(int nr) {
    SV* out = NEWSV(535,nr);
    SvUPGRADE(out,SVt_PV);
    SvCUR_set(out,nr);
    return (out);
}