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Re: Where did the output go and question regarding return values of getopt_long()


"Larry Hall" wrote
At 10:14 AM 12/19/2004, you wrote:
Hello, consider this c++-function:

void
handle_command_line(int argc,
                  char* const argv[],
                  bool& verbose,
                  vector<string>& numbers)
{
 const int id_numbers = 4711;
 const int id_verbose = 4712;
 const int id_help = 4713;

 const option long_options[] =
 {
    {"numbers", 1, NULL, id_numbers},
    {"verbose", 0, NULL, id_verbose},
    {"help", 0, NULL, id_help},
    {NULL, 0, NULL, 0}
 };

const char* const short_options = "";

int c = 0;

 while((c = getopt_long(
           argc,
           argv,
           short_options,
           long_options,
           NULL)) != -1)
 {
    switch(c)
    {
       cout << "c = " << c << endl; /* Never shown on screen... */

       case id_numbers:
       {
          cout << "Calling extract_numbers() with " << optarg << endl;

extract_numbers(optarg, numbers);

          break;
       }
       case id_verbose:
       {
          cout << "Setting verbose = true" << endl;

verbose = true;

break;
}
case id_help:
{
cout << "TODO: Add short description regarding usage here." << endl;


          exit(EXIT_SUCCESS);
       }
       /* c seems to equal '?' for missing parameter as well... */
       case ':':
       {
          cerr << "Missing parameter." << endl;

          break;
       }
       /* Only triggers for unknown options beginning with -- */
       case '?':
       {
          cerr << "Ignoring unknown option." << endl;

          break;
       }
       default:
       {
          /* Throw exception? */
          cerr << "Should not be reached." << endl;
       }
    }
 }
}

My first question is about the
cout << "c = " << c << endl;
inside the switch. I never see this output, why? I tried writing the output to a file as well but that file was empty when the program finished. All other "output-statements" are displayed just fine in this function (and the rest of the program).

Did you look at the warning you get from the line in question?


warning: unreachable code at beginning of switch statement



Lol, of course! It's not reachable...I should've seen that. Anyway, I always compile with -Wall -W -ansi -pedantic and my homebrewn gcc-3.4.3 didn't yield any warnings at all.


Thanks for the help, Larry! One question answered. I'm still wondering about the return values of getopt_long(), though, and I will try the same code on Fedora as soon as I get it setup properly on my laptop.

/ Mikael

-- Larry Hall http://www.rfk.com RFK Partners, Inc. (508) 893-9779 - RFK Office 838 Washington Street (508) 893-9889 - FAX Holliston, MA 01746





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