winsock problem

[Amon Ra]

why doesn't this work:

//skeleton server

#include <winsock.h>
#include <iostream.h>

#define PORTNUM 50000    //port number to be used

void DoSomething (SOCKET);    //use this to do anything with socket

SOCKET Establish (unsigned short PortNum)
{
    char *own_name ;
    SOCKET ret_socket;    //socket to be returned
    sockaddr_in sa;    //internet socket address
    hostent *hp;    //host info

    memset (&sa, 0, sizeof (sockaddr_in));    //clear the address (mem space)
    gethostname (own_name, sizeof (own_name));    //get local host name - our own
    hp = gethostbyname (own_name);    //retrieve address info
    if (hp == NULL)    //hopefully we do exist, and we wont get that error
        return INVALID_SOCKET;    
    sa.sin_family = hp->h_addrtype;    //our host address
    sa.sin_port = htons (PortNum);    //our port number
    ret_socket = socket (AF_INET, SOCK_STREAM, 0);    //create the socket
    if (ret_socket == INVALID_SOCKET)    //failed to create socket
        return INVALID_SOCKET;

    //now, we bind the socket to the internet address
    if (bind (ret_socket, (sockaddr *) &sa, sizeof (sockaddr_in)) == SOCKET_ERROR)    {
        closesocket (ret_socket);    //failed to do so, so get rid of the socket
            return INVALID_SOCKET;
    }

    listen (ret_socket, 3);    //make the socket listen
        return ret_socket;
}    //Establish

int main (int argc, char *argv[])
{
    SOCKET my_socket;    //main socket

    if ((my_socket = Establish (PORTNUM)) == INVALID_SOCKET)    {    //plug in the phone
        cout << "Establish: Failed to install socket" << endl;
            return 0;
    }

    for (    ;    ;    )    {    //loop for phone calls
        SOCKET new_socket = accept (my_socket, NULL, NULL);
        if (my_socket == INVALID_SOCKET)    {
            cout << "Error waiting for connection" << endl;
                return 0;
        }

        DoSomething (new_socket);
        closesocket (new_socket);
    }
        return 0;
}

void DoSomething (SOCKET sock)
{
    //do thing with socket
} 

[Amon Ra]

i just found out i forgot to initialize Winsock with WSAStartup (..), so i dont get the Init. failed error..but after a bit of running, the program crashes..

[Amon Ra]

i changed the

char *own_name 

to

char own_name[256]; 

that's the way it was in the tutorial (w/ the 256)
why does that work and not the one before??

[CornedBee]

Did you forget the pointer 1x1 ?

char* ptr;
is a wild pointer, it points to a random location (most likely 0xCCCCCCCC), so you can't use it.
char buf[512];
on the other hand is an array of 512 chars, it already has memory allocated.

[Amon Ra]

ohh ok..that explains why i would get similar errors in other programs..thanks
why do you call it pointer 1x1?

[CornedBee]

I don't know if that exists in English. The 1x1 ("Ein mal Eins" = "One times One") means "the absolute basics", because it's the first thing you learn in school when multiplying. To know that a pointer declared like char* p; points at random memory is part of the absolute basics of pointers.

[Amon Ra]

ooops.. ok..i wont forget again