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The following trivial example program uses getopt() to handle two program options: -n, with no associated value; and -t val, which expects an associated value. | |
#include <unistd.h> | |
#include <stdlib.h> | |
#include <stdio.h> | |
int | |
main(int argc, char *argv[]) | |
{ | |
int flags, opt; | |
int nsecs, tfnd; | |
nsecs = 0; | |
tfnd = 0; | |
flags = 0; | |
while ((opt = getopt(argc, argv, "nt:")) != -1) { | |
switch (opt) { | |
case 'n': | |
flags = 1; | |
break; | |
case 't': | |
nsecs = atoi(optarg); | |
tfnd = 1; | |
break; | |
default: /* '?' */ | |
fprintf(stderr, "Usage: %s [-t nsecs] [-n] name\n", | |
argv[0]); | |
exit(EXIT_FAILURE); | |
} | |
} | |
printf("flags=%d; tfnd=%d; optind=%d\n", flags, tfnd, optind); | |
if (optind >= argc) { | |
fprintf(stderr, "Expected argument after options\n"); | |
exit(EXIT_FAILURE); | |
} | |
printf("name argument = %s\n", argv[optind]); | |
/* Other code omitted */ | |
exit(EXIT_SUCCESS); | |
} | |
The following example program illustrates the use of getopt_long() with most of its features. | |
#include <stdio.h> /* for printf */ | |
#include <stdlib.h> /* for exit */ | |
#include <getopt.h> | |
int | |
main(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", required_argument, 0, 0 }, | |
{"append", no_argument, 0, 0 }, | |
{"delete", required_argument, 0, 0 }, | |
{"verbose", no_argument, 0, 0 }, | |
{"create", required_argument, 0, 'c'}, | |
{"file", required_argument, 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("\n"); | |
break; | |
case '0': | |
case '1': | |
case '2': | |
if (digit_optind != 0 && digit_optind != this_option_optind) | |
printf("digits occur in two different argv-elements.\n"); | |
digit_optind = this_option_optind; | |
printf("option %c\n", c); | |
break; | |
case 'a': | |
printf("option a\n"); | |
break; | |
case 'b': | |
printf("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 '?': | |
break; | |
default: | |
printf("?? getopt returned character code 0%o ??\n", c); | |
} | |
} | |
if (optind < argc) { | |
printf("non-option ARGV-elements: "); | |
while (optind < argc) | |
printf("%s ", argv[optind++]); | |
printf("\n"); | |
} | |
exit(EXIT_SUCCESS); | |
} |
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