gp2rml/gp2rml.c (main): use getopt

gp2rml/gp2rml.c

@@ -1,8 +1,8 @@
 /*
  * gp2rml.c - Convert from gnuplot to RML
  *
- * Written 2010-2013 by Werner Almesberger
- * Copyright 2010-2013 Werner Almesberger
+ * Written 2010-2013, 2015 by Werner Almesberger
+ * Copyright 2010-2013, 2015 Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -35,6 +35,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <unistd.h>
 #include <string.h>
 #include <math.h>
 
@@ -197,42 +198,41 @@ static void usage(const char *name)
 }
 
 
-int main(int argc, const char **argv)
+int main(int argc, char *const *argv)
 {
-	const char *name;
 	FILE *file;
 	char *end;
 	int i;
 	double p[3];
+	int c;
 
-	name = *argv;
+	 while ((c = getopt(argc, argv, "s:")) != EOF)
+		switch (c) {
+		case 's':
+			z_scale = strtod(optarg &end);
+			if (*end)
+				usage(*argv);
+			break;
+		default:
+			usage(*argv);
+		}
 
-	if (argc > 2 && !strcmp(argv[1], "-s")) {
-		if (argc < 3)
-			usage(name);
-		z_scale = strtod(argv[2], &end);
-		if (*end)
-			usage(name);
-		argc -= 2;
-		argv += 2;
-	}
-
-	switch (argc) {
-	case 4:
+	switch (argc - optind) {
+	case 3:
 		file = stdin;
 		break;
-	case 5:
-		file = fopen(argv[4], "r");
+	case 4:
+		file = fopen(argv[optind + 3], "r");
 		if (!file) {
-			perror(argv[4]);
+			perror(argv[optind + 3]);
 			return 1;
 		}
 		break;
 	default:
-		usage(name);
+		usage(*argv);
 	}
 	for (i = 0; i != 3; i++) {
-		p[i] = strtod(argv[i+1], &end);
+		p[i] = strtod(argv[optind + i], &end);
 		/*
 		 * Allow the clearance to have a unit, for consistency in
 		 * mkmk-simple
@@ -240,7 +240,7 @@ int main(int argc, const char **argv)
 		if (!i && *end && !strcmp(end, "mm"))
 			continue;
 		if (*end || p[i] <= 0)
-			usage(name);
+			usage(*argv);
 	}
 
 	process_file(file);