version option; default device 0

src/mainclass.cpp

     " [--up OUTPUT|--up=OUTPUT|-u OUTPUT]" << std::endl <<
     " [--down OUTPUT|--down=OUPUT|-d OUTPUT]" << std::endl <<
     " [--sleep MS|--sleep=MS|-s MS]" << std::endl <<
-    " [--help|-h]" << std::endl;
+    " [--help|-h]" << std::endl <<
+    " [--version|-v]" << std::endl;
   std::cerr << std::endl << "Controls the output pins of a PiFace digital IO."
     << std::endl << std::endl;
   std::cerr << "--device \tSwitch to the provided device."
     << std::endl << "--down \t\tDisable the provided output pin."
     << std::endl << "--sleep \tSleep for the provided amount of milliseconds."
     << std::endl << "--help \t\tDisplay this message."
+    << std::endl << "--version \tDisplay version."
     << std::endl << std::endl;
   std::cerr << "OUTPUT \t: The output pin to enable/disable. 0 <= OUTPUT <= 7."
     << std::endl << "MS \t: The number of milliseconds to sleep. 0 <= MS <= "
     {"down", 1, 0, 'd'},
     {"sleep", 1, 0, 's'},
     {"help", 0, 0, 'h'},
+    {"version", 0, 0, 'v'},
     {0, 0, 0, 0}
   };
   int opt;
   extern int optind;
   extern char* optarg;
   char* endptr;
-  while ((opt = getopt_long(argc_, argv_, "e:u:d:s:h", opts, 0)) != -1)
+  while ((opt = getopt_long(argc_, argv_, "e:u:d:s:hv", opts, 0)) != -1)
   {
-    if (!optarg)
-      return false;
-    long int arg = strtol(optarg, &endptr, 10);
+    long int arg = optarg ? strtol(optarg, &endptr, 10) : 0;
     if (arg < 0)
       return bad_value_();
     if (opt == 'e')
         return bad_value_();
       actions_.push_back([arg]() -> bool
           {
-          if (get_current_device() != -1)
-            pifacedigital_close(get_current_device());
+          pifacedigital_close(get_current_device());
           return pifacedigital_open(set_current_device(arg)) != -1;
           });
     }
         return bad_value_();
       actions_.push_back([arg]() -> bool
           {
+          if (get_current_device() == -1 &&
+            pifacedigital_open(set_current_device(arg)) == -1)
+            return false;
           pifacedigital_write_reg(up_pin(arg), OUTPUT, get_current_device());
           return true;
           });
         return bad_value_();
       actions_.push_back([arg]() -> bool
           {
+          if (get_current_device() == -1 &&
+            pifacedigital_open(set_current_device(arg)) == -1)
+            return false;
           pifacedigital_write_reg(down_pin(arg), OUTPUT, get_current_device());
           return true;
           });
           return true;
           });
     }
+    else if (opt == 'v')
+    {
+      std::cout << "camotion-piface 1.0" << std::endl;
+      actions_.clear();
+      return true;
+    }
+    else if (opt == 'h')
+    {
+      usage();
+      actions_.clear();
+      return true;
+    }
     else
       return false;
   }
 
 int MainClass::execute()
 {
-  if (argc_ <= 2 || !build_actions_())
+  if (argc_ == 1 || !build_actions_())
     return usage();
   for (auto f : actions_)
     if (!f())