flush buffer using socket recv() with non-blocking flag

I've a socket client application that calls the send() api to send some
request data to the sever and then calls the recv() api to receive the
result from it. A fairly typical socket client program. But because this
is a critical application, I would like to have a way to ensure that all the
result data that I'm getting from the recv() api calls are for the last very
last send() request that I've just sent out. So, I'm thinking, I should
call the recv() api in non-blocking mode before I call the send() api to
flush out all the recv() buffer. Would this be a wise idea?

thanks