$header .= '.h';
$cfile .= '.c';
}
-die "usage: $0 input_file\n" unless $#ARGV == 0;
+die "usage: $0 [input_file]\n" unless $#ARGV == -1 || $#ARGV == 0;
-$infile = $ARGV[0];
+$infile = $ARGV[0] || "def_data.in";
if (!defined($header)) {
$header = $infile;
$header =~ s/(\.in)?$/.h/;