Getopt- Passing string parameter for argument

Question

I have a program which takes in multiple command line arguments so I am using getopt. One of my arguments takes in a string as a parameter. Is there anyway to obtain that st

Answer 1

To specify that a flag requires an argument, add a ':' right after the flag in the short_opt variable. To use long arguments, use getopt_long().

Here is a quick example program:

#include 
#include 

int main(int argc, char * argv[]);

int main(int argc, char * argv[])
{
   int             c;
   const char    * short_opt = "hf:";
   struct option   long_opt[] =
   {
      {"help",          no_argument,       NULL, 'h'},
      {"file",          required_argument, NULL, 'f'},
      {NULL,            0,                 NULL, 0  }
   };

   while((c = getopt_long(argc, argv, short_opt, long_opt, NULL)) != -1)
   {
      switch(c)
      {
         case -1:       /* no more arguments */
         case 0:        /* long options toggles */
         break;

         case 'f':
         printf("you entered \"%s\"\n", optarg);
         break;

         case 'h':
         printf("Usage: %s [OPTIONS]\n", argv[0]);
         printf("  -f file                   file\n");
         printf("  -h, --help                print this help and exit\n");
         printf("\n");
         return(0);

         case ':':
         case '?':
         fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
         return(-2);

         default:
         fprintf(stderr, "%s: invalid option -- %c\n", argv[0], c);
         fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
         return(-2);
      };
   };

   return(0);
}