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+/* Argp example #4 -- a program with somewhat more complicated options */
+
+#include <stdlib.h>
+#include <error.h>
+#include <argp.h>
+
+const char *argp_program_version =
+  "argp-ex4 1.0";
+const char *argp_program_bug_address =
+  "<bug-gnu-utils@@prep.ai.mit.edu>";
+
+/* Program documentation.  */
+static char doc[] =
+  "Argp example #4 -- a program with somewhat more complicated\
+options\
+\vThis part of the documentation comes *after* the options;\
+ note that the text is automatically filled, but it's possible\
+ to force a line-break, e.g.\n<-- here.";
+
+/* A description of the arguments we accept.  */
+static char args_doc[] = "ARG1 [STRING...]";
+
+/* Keys for options without short-options.  */
+#define OPT_ABORT  1		/* --abort */
+
+/* The options we understand.  */
+static struct argp_option options[] = {
+  {"verbose",  'v', 0,       0, "Produce verbose output" },
+  {"quiet",    'q', 0,       0, "Don't produce any output" },
+  {"silent",   's', 0,       OPTION_ALIAS },
+  {"output",   'o', "FILE",  0,
+   "Output to FILE instead of standard output" },
+
+  {0,0,0,0, "The following options should be grouped together:" },
+  {"repeat",   'r', "COUNT", OPTION_ARG_OPTIONAL,
+   "Repeat the output COUNT (default 10) times"},
+  {"abort",    OPT_ABORT, 0, 0, "Abort before showing any output"},
+
+  { 0 }
+};
+
+/* Used by @code{main} to communicate with @code{parse_opt}.  */
+struct arguments
+{
+  char *arg1;			/* @var{arg1} */
+  char **strings;		/* [@var{string}@dots{}] */
+  int silent, verbose, abort;	/* @samp{-s}, @samp{-v}, @samp{--abort} */
+  char *output_file;		/* @var{file} arg to @samp{--output} */
+  int repeat_count;		/* @var{count} arg to @samp{--repeat} */
+};
+
+/* Parse a single option.  */
+static error_t
+parse_opt (int key, char *arg, struct argp_state *state)
+{
+  /* Get the @code{input} argument from @code{argp_parse}, which we
+     know is a pointer to our arguments structure.  */
+  struct arguments *arguments = state->input;
+
+  switch (key)
+    {
+    case 'q': case 's':
+      arguments->silent = 1;
+      break;
+    case 'v':
+      arguments->verbose = 1;
+      break;
+    case 'o':
+      arguments->output_file = arg;
+      break;
+    case 'r':
+      arguments->repeat_count = arg ? atoi (arg) : 10;
+      break;
+    case OPT_ABORT:
+      arguments->abort = 1;
+      break;
+
+    case ARGP_KEY_NO_ARGS:
+      argp_usage (state);
+
+    case ARGP_KEY_ARG:
+      /* Here we know that @code{state->arg_num == 0}, since we
+	 force argument parsing to end before any more arguments can
+	 get here.  */
+      arguments->arg1 = arg;
+
+      /* Now we consume all the rest of the arguments.
+	 @code{state->next} is the index in @code{state->argv} of the
+	 next argument to be parsed, which is the first @var{string}
+	 we're interested in, so we can just use
+	 @code{&state->argv[state->next]} as the value for
+	 arguments->strings.
+
+	 @emph{In addition}, by setting @code{state->next} to the end
+	 of the arguments, we can force argp to stop parsing here and
+	 return.  */
+      arguments->strings = &state->argv[state->next];
+      state->next = state->argc;
+
+      break;
+
+    default:
+      return ARGP_ERR_UNKNOWN;
+    }
+  return 0;
+}
+
+/* Our argp parser.  */
+static struct argp argp = { options, parse_opt, args_doc, doc };
+
+int main (int argc, char **argv)
+{
+  int i, j;
+  struct arguments arguments;
+
+  /* Default values.  */
+  arguments.silent = 0;
+  arguments.verbose = 0;
+  arguments.output_file = "-";
+  arguments.repeat_count = 1;
+  arguments.abort = 0;
+
+  /* Parse our arguments; every option seen by @code{parse_opt} will be
+     reflected in @code{arguments}.  */
+  argp_parse (&argp, argc, argv, 0, 0, &arguments);
+
+  if (arguments.abort)
+    error (10, 0, "ABORTED");
+
+  for (i = 0; i < arguments.repeat_count; i++)
+    {
+      printf ("ARG1 = %s\n", arguments.arg1);
+      printf ("STRINGS = ");
+      for (j = 0; arguments.strings[j]; j++)
+	printf (j == 0 ? "%s" : ", %s", arguments.strings[j]);
+      printf ("\n");
+      printf ("OUTPUT_FILE = %s\nVERBOSE = %s\nSILENT = %s\n",
+	      arguments.output_file,
+	      arguments.verbose ? "yes" : "no",
+	      arguments.silent ? "yes" : "no");
+    }
+
+  exit (0);
+}