simple question

[FrEaK85]

Hi,

I'm creating a c++ class for to easily handle multiple connections with sockets. I'd like to work with some kind of events (I'm a vb programmer ) . My class will use a do loop to check for new connections / new messages (non blocking server). Can I possibly pass a pointer to a function from with the actual code to my class. And then call the sub from within my class.

What I'm trying to say is. I want to call a sub in the code where my class is used. But I don't know wich sub yet. So the user has to tell me (with a function possibly) wich function to call when a new connection is made for example.

Thanks,

Walter Brebels

[Technocrat]

If your program is non blocking then why are you looping for new connections? All you have to do is set it up to do a Window Message on connection and disconnection. You can also assign other messages to functions, then you can just call the coresponding class and function.

[FrEaK85]

Ok, so I suppose its not a non blocking server . It uses the select function to handle multiple connections.

here you can see the tutorial for it (i'm new to c++):
http://www.gamedev.net/reference/art...rticle1494.asp

Any idea's?

Thanks

[Technocrat]

AH, I see, this isn't a Windows program persay that's why they aren't using windows messaging to handle the events. But the basic idea is still the same. Where they have:

switch (buffer[0])
  {
  default:
    Disconnect(s);
    cout << "This Client Has Disconnected: " << ClientIp << endl;
    break;
  case 1:
    // DO SOMETHING IF YOU RECEIVE PACKET 1
    break; 
  case 2:
    // DO SOMETHING IF YOU RECEIVE PACKET 2
    break;
  }
} 

Is where you can call the class and function you need. An example would be lets say you setup a message called MSG_DOWNLOAD which has 1 assigned to it. When you send this message over the wire, it would fire in this the case event.

So using the previous code it would go something like this:

switch (buffer[0])
  {
  default:
    Disconnect(s);
    cout << "This Client Has Disconnected: " << ClientIp << endl;
    break;
  case MSG_DOWNLOAD:
    CSocket.Port_Connect(IP,PORT);
    CSocket.Download(sDIR,sFILE_NAME);
    break; 
  case 2:
    // DO SOMETHING IF YOU RECEIVE PACKET 2
    break;
  }
} 

[FrEaK85]

Ok, now I don't understand a thing anymore .
1st: I taught buffer[] containt the recieved message. (Am I Right).

switch (buffer[0])
  {
  default:
    Disconnect(s);
    cout << "This Client Has Disconnected: " << ClientIp << endl;
    break;
  case 1:
    // Here i taught that the user has send "1" to my server. So now i want to call a function in the code that uses my class. With as argument buffer[]
} 

I just want to pass the recieved data to a function in the code that uses my class.

For example, i don't think this is right but i'll give it a try:

Code that uses my class:

bool RecFunction(char Data)
{
}

MyClass.Function(&RecFunction)

Then in my class when i recieve a message i want to call that RecFunction when I recieved a message.

[Technocrat]

Ok let me see if I can get this strait.

What you are after is that a message has been caught that says your program is now going to receive data. Now you want to take the data that is comming in and send it to a function to put it some where. Is this what you are after?

[FrEaK85]

I just recieve a message, doesn't matter wich and all i need to do is pass that message to a function.
But...
I'm making a class and in that class i recieve the message. And i need to pass that message to a function in the code that uses my class.

Do you know vb? In there they are events.
Visual Baisc example:
Private Sub Winsock1_DataArrival(Data As String)
'This sub is triggered everytime the client sends data to Winsock1
End Sub

I need something like this in C++

[Technocrat]

Ok I get it.

There a problem, the tut you are using because its a bit basic. The message receive buffer:

// Recieve The Data and Put into a Buffer Until we know what it is.
    char buffer[1];
    recv(Client[s].ClientSocket,buffer,1,0); 

Is really small. The it is the size of 1 char, so you would be limited in what data & messages you could receive.

All you would need to do is remove the switch buffer part, then pass the buffer to your class and function. Thats all.

[FrEaK85]

I know that

What i don't know is, how to pass the data from within my class to:
a function in the code that uses my class.

[Technocrat]

Ok....I guess I still don't get it.

So your message/data comes in. You get it in the buffer var. You then pass it to a function in your class that handles the messages. ie CSocket.Message(*buffer);

What you want to know is how do you pass it to another function in your class? Another function not in your class?

Maybe you could give me a more specific example with psuedo code or something

[FrEaK85]

No, thats just it I don't want to pass the data to a function IN my class. I want to pass the data to a function THAT ISN'T in my class.





For example the name of my class = MyClass
It has 1 function: SetFunction()


Now the user wants to use my class, the users code:

#include <Myclass.h>

int ParseData(char Data)
{
// parse the data
}

void main()
{
SetFunction()
}

What i want to do is:
I want to call the "ParseData" function from my class when i recieve data. And with the "SetFunction" function i want to tell my class that it is the "ParseData" function that I should call.

You can compare it with multithreading. You say to CreateThread function to call a function by passing a pointer to that function.

Is it making any sense to you?

[Technocrat]

Phew, man so much for this being a simple question. I guess either I need to go back to bed, or maybe you are making this sound to complicated. If you want to call a function from either your main cpp or from a class that is not in the same cpp then all you have to do is make it globally accessable. There are a couple of ways to do that.

Personally I would put it in a header file. So if you want it for main.cpp, make a main.h

Here is a quick one:

#ifndef __MAIN_H__
#define __MAIN_H__

/*---------------------------------*/
                //Libs

/*---------------------------------*/
                //Include

#include <iostream.h> // Input and Output Stuff, needed for cout and such.
#include <winsock.h> // Needed to use Winsock

/*---------------------------------*/
                //Define

#define PORT 4000 // The Port Number of the Server
#define Max_Connections 10 // The Maximum Number of Connections allowed to connect

#define YES 1 // Making 1 as YES, so its easier to understand our code.
#define NO 2  // Making 2 as NO, so its easier to understand our code.

/*---------------------------------*/
                //Global Functions

int ParseData(char Data) ;

/*---------------------------------*/
                //Global VARs

/*---------------------------------*/

#endif // MAIN_H 

Now in your main.cpp and your Myclass.h

Just add #include "Main.h"

I hope this is what you are looking for.

[FrEaK85]

A new start, i think i've said some things wrong

I am creating a dll to simplify the use of multiple connections with winsock.

It has 3 main public functions:
- void Setup()
- bool SetFunction( *Function1) or something like that
- void Shutdown()

------------------------------------------------

when the user has in its code:

void Function1()
{
//blabla1
}

and he does in its main function:

void main()
{
SetFunction(&Function1);
}

-------------------------------------------------

Then when recieve data in my class:
void GetMessage()
{
.... recieved data
// Now I want to call that function 1
.... go on with code
}

----------------------------------------------------

The problem is the GetMessage function is in my dll. And the Function1 is a piece of code that uses my dll


Thanks,

Walter Brebels

[Technocrat]

Ok now THIS makes sense. Now that we are talking DLLs its more clear.

Now that we have gone through all of this I feel bad because I am not sure I can help. I have never used function pointers before. You might search the forum because I seem to remember this topic coming up before. These tutorial's might also help

http://www.gametutorials.com/Tutorials/C++/Cpp_Pg7.htm
Bottom of the page

You can also call DLL based function in a program just like in VB. Again I am not sure how to do that. Again check the about tut

[CornedBee]

// the function pointer must know which type of function it points to
// for example the WNDPROC pointer is defined like this:
typedef LRESULT (CALLBACK* WNDPROC)(HWND, UINT, WPARAM, LPARAM);
// the brackets around the function name are necessary.
// Function pointers don't need the typedefs, so this could happen:
// global function pointer or function?
int *FuncPtr(int);
// This is interpreted as a function named FuncPtr with int* return type

// this is a pointer named FuncPtr to functions with int return type:
int (*FuncPtr)(int);
// This is a little bit complicated, this is why there are typedefs like above
// Now it's easy to declare a pointer to a WNDPROC
WNDPROC pfnWndProc;
// such a pointer is a member of the WNDCLASS and WNDCLASSEX structs

// to assign a value to a function pointer, use the function name without a parameter list.
pfnWndProc = MyWndProc;

// and to call:
FuncPtr = some_func;
int i = FuncPtr(23);
// some people prefer to write
int i = (*FuncPtr)(23);

[Technocrat]

I knew once you got here, you would have the answer

[FrEaK85]

So let me get this straight:

Users code:

#include <MyClass.h>

void DataArrival(int SocketIndex, char Data)
{
     ...
}


void main()
{
      SetFunction(DataArrival);
}

----------------------------------------------------

DLL Code:

void *ptrDataFunc(int, char);

void SetFunction(&Function)
{
       ptrDataFunc = Function;
}

Would something like this work???

Thanks for all your help.

[CornedBee]

void (*ptrDataFunc)(int, char);

void SetFunction(void (*Function)(int, char))
{
       ptrDataFunc = Function;
}

This will work. But better would be

typedef void (*SOCKRECIEVER)(int, char);

SOCKRECIEVER ptrDataFunc;

void SetFunction(SOCKRECIEVER Function)
{
       ptrDataFunc = Function;
}