Can' t add TCP socket to a socket set with SDL_NET

Question

I get this error trying to add my socket to a socket set:

Exception thrown at 0x69702631 (SDL2_net.dll) in PROJECTNAME.exe: 0xC0000005: Access violation reading location 0x00000000.

I am not sure what I am missing. Here is the relating code.

SDL_Init(SDL_INIT_EVERYTHING);
SDLNet_Init();
IPaddress serverIP;

SDLNet_SocketSet socketSet = SDLNet_AllocSocketSet(10); 
if (socketSet = NULL)
{
    printf("Failed to create the socket set: %s\n", SDLNet_GetError);
}

if (SDLNet_ResolveHost(&serverIP, NULL, 1234) == -1)
{
    printf("SDLNet_ResolveHost: %s \n", SDLNet_GetError());
    exit(1);
}

TCPsocket serverSocket;
serverSocket = SDLNet_TCP_Open(&serverIP); 

if (!serverSocket)
{
    printf("SDLNet_TCP_Open: %s\n", SDLNet_GetError());

}
else
{
    printf("Successfully created server socket \n");
}
int numused;

numused = SDLNet_TCP_AddSocket(socketSet, serverSocket);
if (numused == -1)
{
    printf("SDLNet_Addsocket: %s \n", SDLNet_GetError());
    while (1)
    {
        printf("1");
    }
}

Any help would be appreciated.

Answer 1

There are several typos:

if (socketSet = NULL)

Assigning NULL to socketSet, which makes the condition false and therefore later you are using it to call SDLNet_TCP_AddSocket with a null pointer.

printf("Failed to create the socket set: %s\n", SDLNet_GetError);

Missing ().

In general, it is a good idea to enable as many warnings as possible to avoid trivial typos like these.