use Win32::API;

my $GetWindowsDirectory = new Win32::API(
  "KERNEL32","GetWindowsDirectoryA","PN","N"
);

sub GetWindowsDirectory {
  my $buffer = "\0" x 255;
  $GetWindowsDirectory->Call($buffer,length $buffer);
  $buffer =~ tr/\0//d;
  return $buffer;
};

print GetWindowsDirectory();