Help me with my game command please :<

[FocusedSG]

I'm currently adding a new feature "/msg" to a game that I'm modifying. The command works like "/msg name message". However, I'm having issue to identify which is the name and which is the message. Is using substring function possible to create this command?

[Ganado]

You could use substring to find when the 2nd space is, yes.
Another way to do is to combine the >> operator with std::getline.

// Example program
#include <iostream>
#include <string>

int main()
{
    std::string command;
    
    std::cout << ">";
    std::cin >> command;
    
    if (command == "/msg")
    {
        std::string username;
        std::cin >> username;
        
        std::string command_contents;
        std::getline(std::cin, command_contents);
  
        std::cout << "Sending the message \"" << command_contents << "\" to username \"" << username << "\"" << std::endl;
    }
}

>/msg aaa bbb ccc
Sending the message " bbb ccc" to username "aaa"

Note this isn't perfect, because it leaves the space at the beginning of the message, but logic can be easily added to remove this.

[FocusedSG]

Umm... could you show me how do you do it using substring? I'm kinda slow on this.

[Ganado]

If you show an attempt at solving your problem it will help all of us.

Some examples of using substr are in:
http://www.cplusplus.com/reference/string/string/substr/

You might also be interested in find:
http://www.cplusplus.com/reference/string/string/find/
For example, you could use find to look for spaces.

[FocusedSG]

This is my code. However, string "name" and string "message" is not called, because that is that part that I'm confused with.

else if (str.substr(0, 5) == "/msg ") {
						ENetPeer * currentPeer;

						for (currentPeer = server->peers;
							currentPeer < &server->peers[server->peerCount];
							++currentPeer)
						{
							if (currentPeer->state != ENET_PEER_STATE_CONNECTED)
								continue;

							

							if (((PlayerInfo*)(currentPeer->data))->rawName == name) {
								if (((PlayerInfo*)(currentPeer->data))->haveGrowId == false) continue;
								GamePacket ps = packetEnd(appendString(appendString(createPacket(), "OnConsoleMessage"), "`o>> Private msg from `0" + ((PlayerInfo*)(peer->data))->trueName + "`o (`$in" + ((PlayerInfo*)(peer->data))->currentWorld + "`o) : " + message + "`o"));
								ENetPacket * packet = enet_packet_create(ps.data,
									ps.len,
									ENET_PACKET_FLAG_RELIABLE);
								enet_peer_send(currentPeer, 0, packet);
								delete ps.data;

							}
						}
					}

"/msg name message"
How do I obtain string name and string message?
I've read all the tutorials on this forum on how to find string between 2 spaces using substring, but I still don't get it...

[Satan]

By the way you can also use string stream

#include <iostream>
#include <string>
#include <sstream>

int main() {

	std::string message{ "/msg god Hello god, can I please have the last cookie?" }; 
	std::istringstream iss{ message };

	std::string command;
	iss >> command;

	std::string username;
	iss >> username;

	std::string msg;
	getline(iss, msg);

	std::cout << "Command: " << command << "\nUsername: " << username << "\nMessage: " << msg;

	std::cin.get();
}

[Ganado]

If you must use substr, here's one way to do it.
In the end, you'll get a string for "username", and a string for the actual message itself. Do with that what you will.

// Example program
#include <iostream>
#include <string>

///
/// Parses a command sent to see if it's a /msg command,
/// and if so, returns true and puts the username and message to be sent
/// into username_out and message_out, respectively.
///
bool parse_message_command(const std::string full_command, std::string& username_out, std::string& message_out)
{
    const std::string msg_token = "/msg ";
    
    if (full_command.substr(0, msg_token.size()) == msg_token)
    {
        // assumes username immediately starts at index[5]
        size_t space_after_username_index = full_command.find(" ", msg_token.size());
        
        if (space_after_username_index != std::string::npos)
        {
            username_out = full_command.substr(msg_token.size(), space_after_username_index - msg_token.size());
            message_out  = full_command.substr(space_after_username_index);
            
            if (message_out.size() >= 1)
                message_out.erase(0, 1); // pop initial space off, if any.
            
            return (message_out != "") && (username_out != "");
        }
        else
        {
            return false;
        }
    }

    return false;
}

int main()
{
    // get the username and message from user input
    std::string full_command;
    std::cout << ">";
    std::getline(std::cin, full_command);
    
    // variables to store the username and message in
    std::string username;
    std::string message;
    
    // get the username and message
    if (parse_message_command(full_command, username, message))
    {
        // use the username and message
        std::cout << "Sending message \"" << message << "\" to \"" << username << "\"..." << std::endl;
    }
    else
    {
        std::cout << "Unknown command or incorrect syntax" << std::endl;
    }
}

>/msg Charlie This is a message for Charlie!!!
Sending message "This is a message for Charlie!!!" to "Charlie"...

>/msg
Unknown command or incorrect syntax

>/msg Charlie
Unknown command or incorrect syntax

This also assumes there's only 1 space between the /msg and the username, and the actual message. If you want whitespace between the tokens to not matter, there is a different solution.

[Ganado]

Here's a method that doesn't care about whitespace between "/msg" and "username" and "the actual message". I would prefer this to the substr mess...

   
#include <iostream>
#include <string>
#include <sstream>

///
/// Parses a command sent to see if it's a /msg command,
/// and if so, returns true and puts the username and message to be sent
/// into username_out and message_out, respectively.
///
bool parse_message_command(const std::string full_command, std::string& username_out, std::string& message_out)
{
    std::istringstream iss(full_command);
    std::string msg_token;
    if (iss >> msg_token && msg_token == "/msg")
    {
        std::string username_token;
        if (iss >> username_token)
        {
            std::string start_of_message;
            
            // get first token of the actual message
            if (iss >> start_of_message)
            {
                std::string rest_of_message;
                getline(iss, rest_of_message);
                
                message_out = start_of_message + rest_of_message;
                username_out = username_token;
                
                return true;
            }
            else
            {
                return false;
            }
        }
        else
        {
            return false;
        }
    }
    else
    {
        return false;
    }
}

int main()
{
    // get the username and message from user input
    std::string full_command;
    std::cout << ">";
    std::getline(std::cin, full_command);
    
    // variables to store the username and message in
    std::string username;
    std::string message;

    // get the username and message
    if (parse_message_command(full_command, username, message))
    {
        // use the username and message
        std::cout << "Sending message \"" << message << "\" to \"" << username << "\"..." << std::endl;
    }
    else
    {
        std::cout << "Unknown command or incorrect syntax" << std::endl;
    }
}

>/msg    Charlie      Message for....       Charlie!
Sending message "Message for....       Charlie!" to "Charlie"...