using typedef in advance

Question

I have looked in winsock2.h, and I find that, it confuse me alot:

  typedef SOCKET (WSAAPI *LPFN_ACCEPT)(SOCKET s,struct sockaddr *addr,int *addrlen);

  typedef int (WSAAPI *LPFN_BIND)(SOCKET s,const struct sockaddr *name,int namelen);

  typedef int (WSAAPI *LPFN_CLOSESOCKET)(SOCKET s);

  typedef int (WSAAPI *LPFN_CONNECT)(SOCKET s,const struct sockaddr *name,int namelen);

  typedef int (WSAAPI *LPFN_IOCTLSOCKET)(SOCKET s,__LONG32 cmd,u_long *argp);

  typedef int (WSAAPI *LPFN_GETPEERNAME)(SOCKET s,struct sockaddr *name,int *namelen);

anyone can explain of this situation of using typedef? It would be so appriciate :)

I assume `WSAAPI` is yet another Windows/VS extension (or a macro expanding to one). Otherwise, it's just using typedef to assign names to five function pointer types returning `int`, and to one function function pointer type returning `SOCKET` — Useless, Aug 19 '20 at 15:39

score 0 · Answer 1 · answered Aug 19 '20 at 15:38

0

You are looking at a typedef for a function pointer. For example: typedef SOCKET (WSAAPI *LPFN_ACCEPT)(SOCKET s,struct sockaddr *addr,int *addrlen); declares a function called LPFN_ACCEPT which takes a SOCKET s, struct sockaddr *addr, and an int *addrlen as arguments and returns a SOCKET. The WSAAPI declares the calling convention for this function pointer.

answered Aug 19 '20 at 15:38

Kellen Cataldo

33
4

thanks you, for the WSAAPI explanation, – Chu Viet Huong Aug 19 '20 at 15:45

using typedef in advance

1 Answers1