A getopt.c for your amusement

Python/getopt.c

+/* An implementation of getopt() by Amrit Prem */
+
+#include <stdio.h>
+#include <string.h>
+
+#define bool int
+#define TRUE  1
+#define FALSE 0
+#define EOS   '\0'
+
+bool    opterr = TRUE;          /* generate error messages */
+int     optind = 1;             /* index into argv array   */
+char *  optarg = NULL;          /* optional argument       */
+
+
+int getopt(int argc, char *argv[], const char optstring[])
+{
+   static   char *opt_ptr = "";
+   register char *ptr;
+	    int   option;
+
+   if (*opt_ptr == EOS) {
+
+      if (optind >= argc || argv[optind][0] != '-')
+	 return -1;
+
+      else if (strcmp(argv[optind], "--") == 0) {
+	 ++optind;
+	 return -1;
+      }
+
+      opt_ptr = argv[optind++] + 1;
+   }
+
+   if ((ptr = strchr(optstring, option = *opt_ptr++)) == NULL) {
+      if (opterr)
+	 fprintf(stderr, "Unknown option: -%c\n", option);
+
+      return '?';
+   }
+
+   if (*(ptr + 1) == ':') {
+      if (optind >= argc) {
+	 if (opterr)
+	    fprintf(stderr, "Argument expected for the -%c option\n", option);
+
+	 return '?';
+      }
+
+      optarg = argv[optind++];
+   }
+
+   return option;
+}