Query About Socket Programming

Is there an in built function in C Programming(LINUX Platform of course) which can check whether a Client is still connected to the Server or not in a Socket Program. I had a problem with a Server-Client Socket Program where once the Server doesn't authenticate a Client, the Server Program Terminates but the Client program is still running even after the connection is lost....

Assuming a TCP socket, the client (or server) won't know the other side closed down until a recv(2) on the socket returns 0.