1  /* Example of Parsing Arguments with getopt.
       2     Copyright (C) 1991-2023 Free Software Foundation, Inc.
       3  
       4     This program is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU General Public License
       6     as published by the Free Software Foundation; either version 2
       7     of the License, or (at your option) any later version.
       8  
       9     This program is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12     GNU General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program; if not, see <https://www.gnu.org/licenses/>.
      16  */
      17  
      18  /*@group*/
      19  #include <ctype.h>
      20  #include <stdio.h>
      21  #include <stdlib.h>
      22  #include <unistd.h>
      23  
      24  int
      25  main (int argc, char **argv)
      26  {
      27    int aflag = 0;
      28    int bflag = 0;
      29    char *cvalue = NULL;
      30    int index;
      31    int c;
      32  
      33    opterr = 0;
      34  /*@end group*/
      35  
      36  /*@group*/
      37    while ((c = getopt (argc, argv, "abc:")) != -1)
      38      switch (c)
      39        {
      40        case 'a':
      41          aflag = 1;
      42          break;
      43        case 'b':
      44          bflag = 1;
      45          break;
      46        case 'c':
      47          cvalue = optarg;
      48          break;
      49        case '?':
      50          if (optopt == 'c')
      51            fprintf (stderr, "Option -%c requires an argument.\n", optopt);
      52          else if (isprint (optopt))
      53            fprintf (stderr, "Unknown option `-%c'.\n", optopt);
      54          else
      55            fprintf (stderr,
      56                     "Unknown option character `\\x%x'.\n",
      57                     optopt);
      58          return 1;
      59        default:
      60          abort ();
      61        }
      62  /*@end group*/
      63  
      64  /*@group*/
      65    printf ("aflag = %d, bflag = %d, cvalue = %s\n",
      66  	  aflag, bflag, cvalue);
      67  
      68    for (index = optind; index < argc; index++)
      69      printf ("Non-option argument %s\n", argv[index]);
      70    return 0;
      71  }
      72  /*@end group*/