GNU C Library (libc) Programming Guide - Getopt Long Option Example

25.2.4 Example of Parsing Long Options with getopt_long

 #include <stdio.h>
 #include <stdlib.h>
 #include <getopt.h>
 
 /* Flag set by `--verbose'. */
 static int verbose_flag;
 
 int
 main (argc, argv)
 int argc;
 char **argv;
 {
 int c;
 
 while (1)
 {
 static struct option long_options[] =
 {
 /* These options set a flag. */
 {"verbose", no_argument, &verbose_flag, 1},
 {"brief", no_argument, &verbose_flag, 0},
 /* These options don't set a flag.
 We distinguish them by their indices. */
 {"add", no_argument, 0, 'a'},
 {"append", no_argument, 0, 'b'},
 {"delete", required_argument, 0, 'd'},
 {"create", required_argument, 0, 'c'},
 {"file", required_argument, 0, 'f'},
 {0, 0, 0, 0}
 };
 /* getopt_long stores the option index here. */
 int option_index = 0;
 
 c = getopt_long (argc, argv, "abc:d:f:",
 long_options, &option_index);
 
 /* Detect the end of the options. */
 if (c == -1)
 break;
 
 switch (c)
 {
 case 0:
 /* If this option set a flag, do nothing else now. */
 if (long_options[option_index].flag != 0)
 break;
 printf ("option %s", long_options[option_index].name);
 if (optarg)
 printf (" with arg %s", optarg);
 printf ("\n");
 break;
 
 case 'a':
 puts ("option -a\n");
 break;
 
 case 'b':
 puts ("option -b\n");
 break;
 
 case 'c':
 printf ("option -c with value `%s'\n", optarg);
 break;
 
 case 'd':
 printf ("option -d with value `%s'\n", optarg);
 break;
 
 case 'f':
 printf ("option -f with value `%s'\n", optarg);
 break;
 
 case '?':
 /* getopt_long already printed an error message. */
 break;
 
 default:
 abort ();
 }
 }
 
 /* Instead of reporting `--verbose'
 and `--brief' as they are encountered,
 we report the final status resulting from them. */
 if (verbose_flag)
 puts ("verbose flag is set");
 
 /* Print any remaining command line arguments (not options). */
 if (optind < argc)
 {
 printf ("non-option ARGV-elements: ");
 while (optind < argc)
 printf ("%s ", argv[optind++]);
 putchar ('\n');
 }
 
 exit (0);
 }