my @files = qw( foo.zip twotwo.doc three.one.four.ppt four );
  my ( @only_names, @only_exts );
  foreach ( @files )
  {
      if ( m/^ (.*?) (?:\.([^.]+))? $/x )
      {
          push @only_names, $1;
          push @only_exts,  $2; # might be undef
      }
      else
      {
          warn "couldn't parse '$!'";
      }
  }

  # only for debugging output
  foreach ( @only_exts ) { $_ = 'undef' unless defined $_ }

  print "names = [ @only_names ]\n",
        "exts  = [ @only_exts ]\n";