isPending(pendingError) useless

[Wakan]

Please,
some can explain how to use isPending(pendingError) to realize
that the other end of the socket is disconnected?
I'm trying this:

   setKeepAlive() ;
   while(!isPending(pendingError,0)) {
       if(isPending(pendingInput)) {
           nBytesAvail = peek(str,500);
           nBytesRead = readData(str,nBytesAvail);
          
           if(nBytesAvail > 0) {
               .... 
           }
           else break;   // if this break is missing, it doesn't 
realize that the connection is down, but loops forever, so 
isPending(pendingError,0) doesn't work
       }
   }

If the client disconnects because a network error, the only way to know that
is to reduce the /proc/sys/net/ipv4/tcp_keepalive_time to 30
and tcp_keepalive_probe to 3 (has already suggested by someone in this list)
Is there a way to work better?
I tried to while(1) instead of while(!isPending(pendingError,0)) and if 
works in the
same way...is it right? so how to use isPending(pendingError)?
Thanks in advance