use strict;
use warnings;

use Win32::API;

Win32::API->Import('kernel32.dll', 'DWORD GetCurrentProcessId()') or
  die "Can't import GetCurrentProcessId: $^E\n";

my $procid = GetCurrentProcessId();

if (defined $procid) {
  print "Returned '$procid'\n";
}
else {
  print "Returned <undef>\n";
}