The fd_set structure is used by various Windows Sockets functions and service providers, such as the select function, to place sockets into a “set” for various purposes, such as testing a given socket for readability using the readfds parameter of the select function.
typedef struct fd_set {
u_int fd_count;
SOCKET fd_array[FD_SETSIZE];
} fd_set, FD_SET, *PFD_SET, *LPFD_SET;
fd_count
The number of sockets in the set.
fd_array
An array of sockets that are in the set.
Header: Declared in winsock2.h.
Library: Use ws2_32.lib.