Wrote the check_num_args() function; still need to integrate it into the program. Also wrote a help text that is printed with -h flag.

main.cpp

@@ -49,6 +49,24 @@ const float BASE_BOUNCE_RAD = (BASE_BOUNCE_DEG / 180.0) * M_PI;
 const float BASE_SPEED_COMPONENTS = 15;
 const float BASE_SPEED = sqrt(powf(BASE_SPEED_COMPONENTS, 2) * 2);
 
+std::string HELP_TEXT = "\nnetpong - A networked pong game for the internet era.\n"
+			"\n"
+			"Usage: \n"
+			"netpong [MODE] [ADDRESS|CODE]\n"
+			"\n"
+			"MODE: \n"
+			"-S : Server mode. Starts a server to allow the other player to connect.\n"
+			"IP address must be specified. Port is optional, 6500 is used as default.\n"
+			"\n"
+			"-C: Client mode. Connects to a server, using the provided connection code.\n"
+			"\n"
+			"If no mode is specified, single player mode is used as default.\n"
+			"\n"
+			"CONTROLS:"
+			"\'W\' and \'S\' control left paddle (AKA client paddle)\n"
+			"Up and Down arrow keys control right paddle (AKA server paddle)\n";
+			
+
 /* Simple function to return 1 if a value is positive, and -1 if it is negative */
 int signum(int num) {
 	int retval = 0;
@@ -77,11 +95,23 @@ raylib::Vector2 changeVelocityAfterCollision(Paddle paddle, Ball ball) {
 }
 
 /* Checks the number and type of the command-line arguments. Throws an exception
-   if the args are invalid. */
+   if the args are invalid. DOES NOT PROCESS VALID ARGUMENTS. */
 void check_num_args(int argc, char** argv) {
-	
+	if (argc > 3) {
-	
+		throw std::invalid_argument("ARGUMENT ERROR: Too many arguments. To view syntax, use -h or --help.");
-	
+	}
+	if (argc > 1) { // Either server or client mode
+		if (std::string(argv[1]) == "-S" && argc < 3) { // Server mode but no address
+			throw std::invalid_argument("ARGUMENT ERROR: Server mode specified without any address.");
+		}
+		if (std::string(argv[1]) == "-C" && argc < 3) { // Client mode but no code
+			throw std::invalid_argument("ARGUMENT ERRROR: Client mode specified without any code.");
+		}
+		if (std::string(argv[1]) == "-h" || std::string(argv[1]) == "--help") {
+			throw new std::invalid_argument(HELP_TEXT); // I am abusing the exception mechanism here, so that I can ensure that the caller quits the program.
+		}
+	}
+	return;
 }
 
 /* This function checks the command-line arguments passed to the program.
@@ -188,6 +218,19 @@ GameType check_server_client(int argc, char** argv) {
 }
 
 int main(int argc, char** argv) {
+	/* Check the number of command-line arguments */
+	try {
+		check_num_args(argc, argv);
+	} catch (std::invalid_argument& inv) {
+		std::cout << inv.what() << std::endl;
+		return -1;
+	}
+	
+	/* From here on, we assume that:
+		a. The program was started in single player mode, OR
+		b. The program was started in server mode, and an address was given, OR
+		c. The program was started in client mode, and a code was given. */
+	
 	/* Check if game was started in server or client mode, and set appropriate variables */
 
 	/* GameType struct, to define whether the game is in single or multi-player mode, and

todo.txt

@@ -9,3 +9,4 @@
 9. Allow the user to specify which paddle they want to control, in multi-player mode.
 10. Try to make the ball go between screens.
 11. Change the networking code, so that a single server can connect two clients with each other. The server should provide player 1 with a code, and player 2 can connect with player 1 using that code (essentially like a room).
+12. Add a --help option, that displays information about the game and how to run it.