FD_SET trouble using winsock.

I find this kind of strange but when I use the FD_SET macro in my program everything compiles fine but when I run the executable it crashes.

Code:

---

SOCKET test;
fd_set read_check;

FD_SET(test, &read_check);

---

Any suggestions why this happens ?

EDIT: I'm using the mingw c/c++ compilers and Code::Blocks.

Did you initialise the socket variable test?
Did you FD_ZERO the set before using it?

I thought I did, but when I created a new project just for testing it all worked perfectly. The trouble is in a socket class I'm writing so I have to double check the class code it seems.

If it wasn't for your reply I would not have checked this because I was absolutely sertain I had initialized the socket and also FD_ZERO the set. Thank you! :D