title: Specify port number in TCP client socket
body: <p>I am writing an TCP client socket using C/C++.
    How could I specify certain port number in my client socket?
    Say the client socket is going to have two connections with the same server, 
    and the second connection should use the same local(client side) port number 
    to connect. How could pass the parameter into my code?</p>
  
  <p>local port number is decided right after connect()? Or is it stored in the sock_new=socket()?</p>
  
  <p>Thanks in advance.</p>