Minor changes

check_input.cpp

@@ -18,10 +18,10 @@ GameType check_server(char* ip_text, char* port_text, const int if_mode) {
 
 	/* Check if IP address and port are in valid forms */
 	if (check_ip_ver(ip_text) < 0) {
-		throw std::invalid_argument("Invalid IP address");
+		throw std::invalid_argument("Invalid IP address.");
 	}
 	if (port_to_num(port_text) < 0) {
-		throw std::invalid_argument("Invalid port");
+		throw std::invalid_argument("Invalid port.");
 	}
 
 	/* From here on, we assume that the IP and port are valid */