$var = ($type)SvPV_nolen($arg)

##</code><code>##

	if (SvOK($arg)) 
	   $var = ($type)SvPV_nolen($arg);
	else
	   $var = INT2PTR($type,SvIV($arg))

##</code><code>##

INPUT

T_PV
	if (SvOK($arg)) 
	   $var = ($type)SvPV_nolen($arg);
	else
	   $var = INT2PTR($type,SvIV($arg))

##</code><code>##

use strict;
use warnings;
use Devel::Peek;

use Inline C => Config =>
  BUILD_NOISY => 1, # verbose build
  FORCE_BUILD => 1, # re-build whenever the script is run
  CLEAN_AFTER_BUILD => 0, # don't clean up the build directory
;

use Inline C =><<'EOC';

unsigned char * foo(unsigned char *name) {
  if(name) printf("name is: %s\n", name);
  else printf("NULL input (undef) was detected\n");
  return(name);
}

EOC

my $x = foo(undef);
Dump($x);

my $y = foo("hello world");
Dump($y);

my $z = foo('');
Dump $z;