#include <iostream>
#include <string>

#include <unistd.h>

using namespace std;

const char * ARG_STR{"hG:P::"};

int main(int argc, char * argv[]){
    char opt;
    char punct{'!'};
    string greeting{"Hello World"};

    // this controls error reporting.
    opterr = 0;


    while ((opt = getopt(argc, argv, ARG_STR)) != -1) {
        switch(opt) {
           case 'h':
              cout << "h: calling help routine " << endl;
              cout << endl;
              break;
           case 'G':
              greeting = optarg;
              cout << "G: The greeting will be " << greeting << endl;
              cout << endl;
              break;
           case 'P':
              if (optarg != nullptr) {
                 punct = optarg[0];
              } else {
                 punct = ' ';
              }
              cout << "P: the punctuation is \""<< punct  << "\"" << endl;
              cout << endl;
              break;
           default:
              cout  << "Default got " << opt << " which is at position " 
                    << optind << endl;
              cout << "\tOptopt contains " << static_cast<char>(optopt) << endl;
              cout << "\tBut that is not a valid argument" << endl;
              cout << endl;
        }
        cout << endl;
    }

    cout << "optind is " << optind << endl;
    if (optind < argc) {
        cout << "That is " << argv[optind] << endl;
    } else {
        cout << "That is past the end of the args. " << endl;
    }

    cout << endl;
    cout << greeting << punct << endl;

    return 0;
}