using getopt in C

[g3k0]

Greetings, I am using the getopt function and I had a question. Is there anyway to easily, not require an argument after the r - example

./webserver -p 5000 -r

rather than

./webserver -p 5000 -r /asd

because it does this to me
[bwhit132@csunix webserver]$ ./webserver -p 5000 -r
./webserver: option requires an argument -- r


I want to allow the option but not have it as a necessity.


this is what im doing with it

void processargs(int argc, char **argv) {
  int dirSize = 100;
  int next_option;
  const char* short_options = "p:r:";
  do {
    next_option = getopt(argc, argv, short_options);
    if (next_option != -1) {
      switch (next_option)
      {
        case 'p': /* -p -- port option  */
          port = optarg;
          break;
	case 'r':
		
	  myPath = malloc(dirSize);		//allocate because we are copying into a null ptr
	  while (getcwd(myPath,dirSize) == NULL){   //if the directory has a long name, reallocate size
		  free(myPath);
		  dirSize *= 2;
		  myPath = malloc(dirSize);		  
	  }
	 downPath = optarg;	
	 if (downPath == NULL){
		  printf("\nHAHAAAAA NULL BOY\n");
	 } else { printf("\n%s\n",downPath); }
	  break;
        default:
          /* Unknown option detected. Print it to standard
                output, and exit with exit code zero (normal termination). */
          fprintf(stderr, USAGE_STRING);
          exit(1);
  
      }
    }
  } while (next_option != -1);
  
  if (port == NULL) {
          fprintf(stderr, USAGE_STRING);
          exit(1);
  }
}

Edit: In case you were wondering I was just testing with the whole hahaha null boy thing..

[Mr. C.]

man 3 getopt

optstring is a string containing the legitimate option characters. If
such a character is followed by a colon, the option requires an argu-
ment, so getopt places a pointer to the following text in the same
argv-element, or the text of the following argv-element, in optarg.
Two colons mean an option takes an optional arg; if there is text in
the current argv-element, it is returned in optarg, otherwise optarg is
set to zero. This is a GNU extension. If optstring contains W fol-
lowed by a semicolon, then -W foo is treated as the long option --foo.
(The -W option is reserved by POSIX.2 for implementation extensions.)
This behaviour is a GNU extension, not available with libraries before
GNU libc 2.

[g3k0]

ohhhh thanks. I was looking at the wrong man page. Thanks for your help