#include <unistd.h> int getopt(int argc, char * const argv[], const char *optstring); extern char *optarg; extern int optind, opterr, optopt; #include <getopt.h> int getopt_long(int argc, char * const argv[], const char *shortopts, const struct option *longopts, int longind);
The external variable optind is the index of the next array element of argv[] to be processed; it communicates from one call of getopt() to the next which element to process.
The getopt_long() function works like getopt() except that it also accepts long options, started out by two dashes. If these take values, it is either in the form --arg=value or --arg value. It takes the additional arguments longopts which is a pointer to the first element of an array of struct option declared in <getopt.h> as
struct option { const char *name; int has_arg; int *flag; int val; };The meaning of the different fields are:
The last element of the array has to be filled with zeroes.
The option_index points to the index of the long option relative to longopts.
#include <stdio.h> int main (argc, argv) int argc; char **argv; { int c; int digit_optind = 0; while (1) { int this_option_optind = optind ? optind : 1; int option_index = 0; static struct option long_options[] = { {"add", 1, 0, 0}, {"append", 0, 0, 0}, {"delete", 1, 0, 0}, {"verbose", 0, 0, 0}, {"create", 1, 0, 'c'}, {"file", 1, 0, 0}, {0, 0, 0, 0} }; c = getopt_long (argc, argv, "abc:d:012", long_options, &option_index); if (c == -1) break; switch (c) { case 0: printf ("option %s", long_options[option_index].name); if (optarg) printf (" with arg %s", optarg); printf ("); break; case '0': case '1': case '2': if (digit_optind != 0 && digit_optind != this_option_optind) printf ("digits occur in two different argv-elements.); digit_optind = this_option_optind; printf ("option %c, c); break; case 'a': printf ("option a); break; case 'b': printf ("option b); break; case 'c': printf ("option c with value `%s', optarg); break; case 'd': printf ("option d with value `%s', optarg); break; case '?': break; default: printf ("?? getopt returned character code 0%o ??, c); } } if (optind < argc) { printf ("non-option ARGV-elements: "); while (optind < argc) printf ("%s ", argv[optind++]); printf ("); } exit (0); }